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# Project Three: Simple World

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Project Three: Simple World

I. Motivation
1. To give you experience in using arrays, pointers, structs, enums, different I/O streams, and
writing program that takes arguments.
2. To let you have fun with an application that is extremely captivating.
II. Introduction
1. Overview
The simple world program we will write for this project simulates a number of creatures running
around in a simple world. The world is an m-by-n two-dimensional grid of squares (The number
m represents the height of the grid and the number n represents the width of the grid.). Each
creature lives in one of the squares, faces in one of the major compass directions (north, east,
south, or west), and belongs to a particular species, which determines how that creature behaves.
Each square also has a specific terrain type.
la
ho
fl
fl
ho
P P P
F F F F
P L L
P
P
H H H H
Figure 1. A 4-by-4 grid, which contains five creatures.
Figure 1 shows a 4-by-4 grid populated by five creatures. Two of them belong to the species
flytrap (whose short name is “fl”), two belong to the species hop (whose short name is “ho”), and
one belongs to the species landmine (whose short name is “la”). The direction of each creature is
represented by the direction of the arrow. For example, the flytrap at the top row is facing east
and the flytrap at the bottom row is facing west. The character in each square indicates the terrain
type of the square. There are four terrain types: plain (P), lake (L), forest (F), and hill (H) (See
Section II-3 for more details). Each creature belongs to one species and each species has an
associated program which controls how each creature of that species behaves (See Section II-2
for more details). Each creature may also have some special abilities, including flying and
archery (See Section II-4 for more details).
Table 1. The list of instructions and their explanations.
hop
The creature moves forward. If moving forward would put the creature
outside the boundaries of the grid, would cause the creature that cannot fly
to land in a “lake” square, or would cause the creature to land on top of
another creature, the hop instruction does nothing.
left The creature turns left 90 degrees to face in a new direction.
right The creature turns right 90 degrees to face in a new direction.
infect
If the square immediately in front of this creature is occupied by a creature of
a different species (which we refer to as an “enemy”), that enemy creature is
infected to become the same as the infecting species. When a creature is
infected, it keeps its position and orientation, but changes its internal species
indicator and begins executing the same program as the infecting creature,
starting at step 1. If the square immediately in front of this creature is empty,
outside the grid, being a forest square, or occupied by a creature of the same
species, the infect instruction does nothing. If the creature has the archery
ability, its infecting action is different (see Section II-4 for more details).
ifempty n
If the square in front of the creature is inside the grid boundary and
unoccupied, jump to step n of the program; otherwise, go on with the next
instruction in sequence.
ifenemy n
If the square the creature is facing is not a “forest” square and is occupied by
a creature of an enemy species, jump to step n; otherwise, go on with the next
instruction.
ifsame n
If the square the creature is facing is not a “forest” square and is occupied by
a creature of the same species, jump to step n; otherwise, go on with the next
instruction.
ifwall n
If the creature is facing the border of the grid (which we imagine as
consisting of a huge wall), or the creature is facing a lake square and it cannot
fly, jump to step n of the program; otherwise, go on with the next instruction
in sequence.
go n This instruction always jumps to step n, independent of any condition.
2. Species Instructions
Each species has an associated program which controls how each creature of that species
behaves. Programs are composed of a sequence of instructions. The instructions that can be
part of a program are listed in Table 1. There are nine legal instructions in total. The last five
instructions have an additional integer argument.
Program is an attribute associated with species. Creatures of the same species have the same
program. However, different species have different programs.
For example, the program of the species flytrap is composed of the following five instructions:
ifenemy 4
left
go 1
infect
go 1
The meaning of each instruction for this example is commented below:
(step 1) ifenemy 4 # If there is an enemy ahead, go to step 4
(step 2) left # Turn left
(step 3) go 1 # Go to step 1
(step 4) infect # Infect the adjacent creature
(step 5) go 1 # Go to step 1
We will simulate the behaviors of all the creatures for a user specified number of rounds. In each
round, creatures take their turns one by one, starting from the first creature. After the first
creature finishes its turn, the second creature begins its turn. So on and so forth. One round ends
with the last creature finishing its turn. Then the next round begins with the first creature taking
its turn. Note that during the simulation, a creature may infect another creature so that the
infected one changes its species. However, the simulation order of the infected creature does not
change.
Each creature also maintains a variable called program counter which stores the index of the
instruction it is going to execute. On each turn of a creature, it executes a number of instructions
of its program, starting from the step indicated by the program counter. A program ordinarily
continues with each new instruction in sequence, although this order can be changed by certain
instructions in the program such as the if*** instructions. In each turn, a creature can execute
any number of if*** or go instructions without relinquishing this turn. Its turn ends only when
the creature executes one of the instructions: hop, left, right, or infect. After its turn ends, the
creature updates the program counter to point to the next instruction, which will be executed at
the beginning of its next turn.
Note that each creature maintains its own program counter, so that two different creatures
belonging to the same species can have different program counters. The indices of the
instructions start from one, i.e., the first instruction of each program is “step 1”. At the very
beginning of the simulation process, the program counters of all the creatures are set to their first
instructions.
3. Terrain Information
In order to simulate the geographical environment of the world, the simple world has the
following four terrain types. Each square in the grid belongs to one of these four types.
1. Plain (P): A square of the plain type is represented as P in the grid. A plain square does not
have any side effects to a creature in it.
2. Lake (L): A square of the lake type is represented as L in the grid. If a creature cannot fly, it
cannot move into a lake square; otherwise, it can move into a lake square. Therefore, a lake
square is treated as an impassible wall for a creature that cannot fly. In summary, if a
creature is facing a lake and it cannot fly, the ifwall instruction should return true. If the
creature is facing a lake and it can fly, the ifwall instruction should return false.
3. Forest (F): A square of the forest type is represented as F in the grid. When a creature is in a
forest square, it cannot be seen by another creature. Therefore, a creature in a forest square
cannot be infected by an enemy creature, unless the enemy has the archery ability (see
Section II-4 for more details on the archery ability). If a creature (no matter whether it has
the archery ability or not) is facing another creature that is in a forest square, the ifempty,
ifsame, and ifenemy instructions should all return false.
4. Hill (H): A square of the hill type is represented as H in the grid. In a hill square, it is rocky
and by default, a creature in that square cannot act quickly. Therefore, a creature in a hill
square can do simulation once every two rounds. For example, if a creature just moves from
a non-hill square into a hill square in one round (assuming that this is the first round), it
should stay idle (i.e., do not execute any instructions) in the second round. Then, in the third
round, the creature continues to simulate the next instruction. If, by the end of the third
round, the creature still stays in a hill square, it stays idle in the fourth round. It simulates the
next instruction in the fifth round. On the other hand, if, by the end of the third round, the
creature is in a non-hill square, it simulates the next instruction in the fourth round. Note that
if the creature is in the hill square initially, it should be treated as staying idle in the first
round; it simulates the next instruction in the second round. Also note that the side effect of
a hill square is not applied to a creature that can fly.
4. Special Ability of Creature
Each creature might have special abilities (hereafter, referred to as abilities) in the simple world.
There are two kinds of abilities: flying (f) and archery (a). Creatures may have no abilities.
They may also have multiple abilities. The abilities of a creature will be maintained
throughout the whole simulation, even if the creature is infected. Creatures of the same
species may have different sets of abilities. Below are the details of these two abilities.
1. Flying (f): A creature with the flying ability can override the restriction of a lake square and
a hill square. It can move into a lake square. It can simulate its behavior once every round
even if it is in a hill square. If it is in a forest square, the effect of a forest square on it does
not change.
2. Archery (a): For a creature A with the archery ability, if it infects, it will infect the first
creature of an enemy species (if existing) in its facing direction no matter how far they are
away from each other and no matter whether there are creatures of the same species as A in
between them. A creature with archery ability can see enemies in forest. Therefore, it can
infect the enemy even if the enemy is in a forest square.
III. Available Types
In completing this project, you will have the following types available to you. They are defined
in the file world_type.h.
const unsigned int MAXSPECIES = 10; // Max number of species in the
// world
const unsigned int MAXPROGRAM = 40; // Max size of a species program
const unsigned int MAXCREATURES = 50; // Max number of creatures in
// the world
const unsigned int MAXHEIGHT = 20; // Max height of the grid
const unsigned int MAXWIDTH = 20; // Max width of the grid
enum direction_t { EAST, SOUTH, WEST, NORTH, DIRECT_SIZE };
/*
// Type: direction_t
// —————-
// This type is used to represent direction, which can take one of
// the four values: East, South, West, and North. The last one,
// DIRECT_SIZE, can be used to indicate the end of this enum type.
// This convention is applied to the other enum types defined below.
*/
enum terrain_t { PLAIN, LAKE, FOREST, HILL, TERRAIN_SIZE };
/*
// Type: terrain_t
// —————-
// This type is used to represent terrain type of a square, which
// can take one of the four values: Plain, Lake, Forest, Hill.
*/
enum ability_t { FLY, ARCH, ABILITY_SIZE };
/*
// Type: ability_t
// —————-
// This type is used to represent special abilities of a creature,
// which can take one of the two values: Flying and Archery.
*/
enum opcode_t { HOP, LEFT, RIGHT, INFECT, IFEMPTY, IFENEMY, IFSAME,
IFWALL, GO, OP_SIZE };
/*
// Type: opcode_t
// ————-
// The type opcode_t is an enumeration of all of the legal
// command names.
*/
struct point_t
{
int r;
int c;
};
/*
// Type: point_t
// ————
// This type is used to represent a point in the grid.
// Its component r corresponds to the row number; its component
// c corresponds to the column number;
*/
const string directName[] = {“east”, “south”, “west”, “north”};
// An array of strings representing the direction name.
const string directShortName[] = {“e”, “s”, “w”, “n”};
// An array of strings representing the short name of direction.
const string terrainName[] = {“plain”, “lake”, “forest”, “hill”};
// An array of strings representing the terrain type name.
const string terrainShortName[] = {“P”, “L”, “F”, “H”};
// An array of strings representing the short name of terrain type.
const string abilityName[] = {“fly”, “arch”};
// An array of strings representing the ability name.
const string abilityShortName[] = {“f”, “a”};
// An array of strings representing the short name of ability.
const string opName[] = {“hop”, “left”, “right”, “infect”,
“ifempty”, “ifenemy”, “ifsame”, “ifwall”, “go”};
// An array of strings representing the command name.
struct instruction_t
{
opcode_t op;
};
/*
// Type: instruction_t
// ——————
// The type instruction_t is used to represent an
// instruction and consists of a pair of an operation
// code and an integer. For some operation code, the
// integer stores the address of the instruction it jumps
// to (e.g., n in the instruction “ifempty n”). The
*/
struct species_t
{
string name;
unsigned int programSize;
instruction_t program[MAXPROGRAM];
};
/*
// Type: species_t
// ——————
// The type species_t is used to represent a species
// and consists of a string, an unsigned int, and an array
// of instruction_t. The string gives the name of the
// species. The unsigned int gives the number of instructions
// in the program of the species. The array stores all the
// instructions in the program according to their sequence.
*/
struct creature_t
{
point_t location;
direction_t direction;
species_t *species;
unsigned int programID;
bool ability[ABILITY_SIZE];
bool hillActive;
};
/*
// Type: creature_t
// ——————
// The type creature_t is used to represent a creature. It
// consists of a point_t, a direction_t, a pointer to
// species_t, an unsigned int, a bool array, and a bool variable.
// The point_t variable location gives the location of the
// species. The direction_t variable direction gives the direction
// of the species. The pointer to species_t variable species
// points to the species the creature belongs to. The unsigned
// int programID gives the index of the instruction to be executed
// in the instruction_t array of the species. The bool array
// ability indicates the set of abilities the creature has. For
// example, if the creature only has FLY ability, you should set
// ability[FLY] to true and ability[ARCH] to false. The bool
// variable hillActive indicates if the creature is able to simulate
// in the current round if the creature is in a hill square. It does
// not serve any other purpose if the creature is not in a hill
// square.
*/
struct grid_t
{
unsigned int height;
unsigned int width;
creature_t *squares[MAXHEIGHT][MAXWIDTH];
terrain_t terrain[MAXHEIGHT][MAXWIDTH];
};
/*
// Type: grid_t
// ——————
// The type grid_t consists of the height and the width of
// the grid, a two-dimensional array of pointers to creature_t,
// and a two-dimensional array of terrain_t type. If there is
// a creature at the point (r, c) in the grid, then squares[r][c]
// stores a pointer to that creature. If point (r, c) is not
// occupied by any creature, then squares[r][c] is a NULL pointer.
// The two-dimensional array terrain stores the terrain type for
// each square in the grid.
*/
struct world_t
{
unsigned int numSpecies;
species_t species[MAXSPECIES];
unsigned int numCreatures;
creature_t creatures[MAXCREATURES];
grid_t grid;
};
/*
// Type: world_t
// ————–
// This type consists of two unsigned ints, an array of species_t,
// an array of creature_t, and a grid_t object. The first unsigned
// int numSpecies specifies the number of species in the creature
// world. The second unsigned int numCreatures specifies the number
// of creatures in the world. All the species are stored in the array
// species and all the creatures are stored in the array creatures.
// The grid is given in the object grid.
*/
IV. File Input
All the species, the programs for all the species, and the initial layout of the creature world are
stored in files and these files will be read by your program to set up the simulation environment.
Note: when you read files, you must use input file stream ifstream. Otherwise, since the
files are read-only on our online judge, you may fail to read the files.
As we described before, each species has an associated program. The program for each species is
stored in a separate file whose name is just the name of that species. For example, the program
for the species flytrap is stored in a file called flytrap.
A file describing a program contains all the instructions of that program in order. Each line lists
just one instruction. The first line lists the first instruction; the second line lists the second
instruction; so on and so forth. Each instruction is one of the nine legal instructions described in
Table 1. The program ends with the end of file or a blank line. Comments may appear after the
blank line or at the end of each instruction line. For example, the program file for the flytrap
species looks like:
ifenemy 4 If there is an enemy, go to step 4.
left If no enemy, turn left.
go 1
infect
go 1
The flytrap sits in one place and spins.
It infects anything which comes in front.
Flytraps do well when they clump.
Note that in writing functions for reading these program files, you should handle the comments
correctly, which means that you should ignore these comments when setting up the program for a
species.
Since there are many species, we stored all of their program files in a directory.
To help you get all the species and their program files, we also have a file telling the directory
where the program files are stored and listing all the species. We call this file a species summary.
The first line of this file shows the directory where all of the program files are stored. The next
lines list all the species, with one species per line. For example, the following is a species
summary file:
creatures
flytrap
hop
landmine
From this file, we can learn that the program files are stored in the directory called creatures
within the current working directory. We have three species to simulate, which are flytrap, hop,
and landmine. By first reading the species summary file, you will know where to find the
program file for each species.
Finally, there is a file describing the initial state of the creature world. We call it a world file. The
first line of this file gives the height of the two-dimensional grid (i.e., the number of rows) and
the second line gives the width of the grid (i.e., the number of columns). Afterwards, it is the
terrain layout of the grid. The terrain layout is indicated by a two-dimensional array of
characters, with each character being one of ‘P’, ‘L’, ‘F’, and ‘H’, corresponding to plain, lake,
forest, and hill types, respectively. The remaining lines of this file describe all the creatures to
simulate and their initial directions, locations, and abilities, with one creature per line. Each of
these lines has the following format:
<species> <initial-direction> <initial-row> <initial-column>
[ability-1] [ability-2]
where <species> is one of the species from the species summary file,
<initial-direction> describes the initial direction and is one of the strings “east”,
“south”, “west”, and “north”. <initial-row> describes the initial row location of the
creature. We use the convention that the top-most row of the grid is row 0 and the row
number increases from top to bottom. <initial-column> describes the initial column
location of the creature. We use the convention that the left-most column of the grid is column
0 and the column number increases from left to right. [ability-i] is optional. It
describes the i-th ability of the creature and is one of the characters ‘f’ and ‘a’, corresponding to
the flying and archery abilities, respectively. Note there could be no ability entry. There is no
specific order on which type should appear first.
An example of a world file looks like:
4
4
PPLL
PPLL
FFHH
FFHH
hop east 2 0 f a
flytrap east 2 2
It says that the size of the grid is 4-by-4 and the top left, top right, bottom left, and bottom right
quadrants are plains, lakes, forests, and hills, respectively. There are two creatures in the world.
The first creature belongs to the species hop. It faces east and lives at point (2, 0) initially. It has
the abilities of flying and archery. The second creature belongs to the species flytrap. It faces east
and lives at point (2, 2) initially. It has no special abilities.
In the simulation, the order on the creatures to simulate is important. This order is
determined by the order that these creatures appear in the world file.
V. Program Arguments
Your program will obtain the names of the species summary file and the world file via program
arguments. Additionally, your program will be told the number of rounds to simulate and
whether it should print the simulation result verbosely or not.
The expected order of arguments is:
<species-summary> <world-file> <rounds> [v|verbose]
The first three arguments are mandatory. They give the name of the species summary file, the
name of the world file, and the number of simulation rounds, respectively. The fourth argument
is optional. If the fourth argument is the string “v” or the string “verbose”, your program should
print the simulation result verbosely, which will be explained later. Otherwise, if it is omitted or
is any other string, your program should print the result concisely, which will also be explained
later. If there are more than four arguments, the remaining arguments are ignored.
Suppose that you program is called p3. It may be invoked by typing in a terminal:
./p3 species world 10 v
Then your program should read the species summary from the file called “species” and the
world file from the file called “world”. The number of simulation rounds is 10. Your program
should print the simulation information verbosely.
VI. Error Checking and Error Message
Your program should check for errors before it starts to simulate the moves of the creatures. If
any error happens, your program should issue an error message and then exit. If there are no
errors happening, then the initial state of the creature world is legal and your program can start
simulating the simple world.
We require you to do the following error checking and print the error message in exactly the
same way as described below. Note that some of the output error message has two lines and each
error message should be ended with a newline character. All error messages should be sent to the
standard output stream cout; none to the standard error stream cerr.
1. Check whether the number of arguments is less than three. If it is less than three, then one of
the mandatory arguments is missing. You should print the following error message:
Error: Missing arguments!
Usage: ./p3 <species-summary> <world-file> <rounds> [v|verbose]
2. Check whether the value <rounds> supplied by the user is negative. If it is negative, you
should print the following error message:
Error: Number of simulation rounds is negative!
3. Check whether file open is successful. If opening species summary file, world file, or any
species program file fails (for example, the file to be opened does not exist), print the following
error message:
Error: Cannot open file <filename>!
where <filename> should be replaced by the name of the file that fails to be opened. If that
file is not in the same directory as your program, you need to include its path in the
<filename>. As you may know, there are multiple ways to specify a path. For us, the path
name should be specified in the most basic way, i.e., “<dir>/<filename>” (not
“./<dir>/<filename>”, “<dir>//filename”, etc.). Once you find a file that cannot be
opened, issue the above error message and terminate your program.
4. Check whether the number of species listed in the species summary file exceeds the maximal
number of species MAXSPECIES. If so, print the following error message:
Error: Too many species!
Maximal number of species is <MAXSPECIES>.
where <MAXSPECIES> should be replaced by the maximal number of species set by your
program.
5. Check whether the number of instructions for a species exceeds the maximal size of a species
program MAXPROGRAM. If so, print the following error message:
Error: Too many instructions for species <SPECIES_NAME>!
Maximal number of instructions is <MAXPROGRAM>.
where <SPECIES_NAME> should be replaced by the name of the species whose program has
more instructions than the maximal number allowed and <MAXPROGRAM> should be replaced
by the maximal size of a species program set by your program.
6. Check whether the instructions are valid. The species program file contains instructions. We
only allow nine instructions as listed in Table 1. Your program needs to check whether the
instruction name is one of the nine legal instruction names listed in the string array opName
(which is defined in Section III). If an instruction name is not recognized, you should print the
following error message:
Error: Instruction <UNKNOWN_INSTRUCTION> is not recognized!
where <UNKNOWN_INSTRUCTION> should be replaced by the name of the unrecognized
instruction. You can assume that for any recognized instruction, it is given in the correct format.
Thus, you don’t need to check whether an integer is appended after the instruction name or not.
If there are multiple unrecognized instruction names, you only need to print out the first one and
then terminate the program.
7. Check whether the grid height given by the world file is legal. A legal grid height is at least
ONE and less than or equal to a maximal value MAXHEIGHT. If the grid height is illegal, print
the following error message:
Error: The grid height is illegal!
8. Check whether the grid width given by the world file is legal. A legal grid width is at least
ONE and less than or equal to a maximal value MAXWIDTH. If the grid width is illegal, print the
following error message:
Error: The grid width is illegal!
9. Check whether the two-dimensional array describing the terrain layout is correct. You can
assume that the height and the width of the array are equal to the correct values. You only need
to check whether each character is the array is one of the valid characters, ‘P’, ‘L’, ‘F’, and ‘H’.
If a character is not valid, print the following error message:
Error: Terrain square (<CHAR> <R> <C>) is invalid!
where <R> should be replaced by the row location of the invalid square, <C> be replaced by the
column location of the square, , and <CHAR> be replaced by the invalid character in the square.
For example, given the following world file:
2
2
PP
PA
flytrap east 0 0 f a
food west 1 1 f
You should print the error message:
Error: Terrain square (A 1 1) is invalid!
If there are multiple invalid characters, you only need to print out the first one and then terminate
the program. The first invalid character has the smallest row number, and among all the invalid
characters with that same smallest row number, the first invalid character has the smallest
column number.
10. Check whether the number of creatures listed in the world file exceeds the maximal number
of creatures MAXCREATURES. If so, print the following error message:
Error: Too many creatures!
Maximal number of creatures is <MAXCREATURES>.
where <MAXCREATURES> should be replaced by the maximal number of creatures allowed by
11. Check whether each creature in the world file belongs to one of the species listed in the
species summary file. If the species for a creature is not recognized, print the following error
message:
where <UNKNOWN_SPECIES> should be replaced by the unrecognized species. If there are
multiple unrecognized species, you only need to print out the first one and then terminate the
program.
12. Check whether the direction string for each creature in the world file is one of the strings in
the array directName (which is defined in Section III). If the direction string is not
recognized, print the following error message:
Error: Direction <UNKNOWN_DIRECTION> is not recognized!
where <UNKNOWN_DIRECTION> should be replaced by the unrecognized direction name. If
there are multiple unrecognized direction names, you only need to print out the first one and then
terminate the program.
13. Check whether each creature is inside the boundary of the grid. If any creature is outside the
boundary, print the following error message:
Error: Creature (<SPECIES> <DIR> <R> <C>) is out of bound!
The grid size is <HEIGHT>-by-<WIDTH>.
where <SPECIES> should be replaced by the species the creature belongs to, <DIR> be
replaced by the direction the creature is facing, <R> be replaced by the row location of the
creature, <C> be replaced by the column location of the creature, <HEIGHT> be replaced by the
height of the grid, and <WIDTH> be replaced by the width of the grid. Here, we use the fourtuple (<SPECIES> <DIR> <R> <C>) to identify the creature. For example, if given the
following world file:
3
3
PPP
PPP
PPP
flytrap east 0 0 f a
hop south 3 2 a
food west 2 1
then, the creature (hop south 3 2) is outside the boundary. Then, the error message should
be:
Error: Creature (hop south 3 2) is out of bound!
The grid size is 3-by-3.
If there are multiple creatures outside the boundary, you only need to print out the first one and
then terminate the program.
14. Check whether each ability of each creature is valid. If an ability is neither of the two valid
characters, ‘f’ and ‘a’, print the following error message:
Error: Creature (<SP> <DIR> <R> <C>) has an invalid ability <ABILITY>!
where the four-tuple (<SP> <DIR> <R> <C>) identifies the creature that has an invalid
ability, and <ABILITY> should be replaced by the invalid ability string. Note that anything that
is not one of the character ‘f’ and ‘a’ is invalid. This includes strings that do not contain
whitespaces but have more than 1 character. For example, for the following world map:
2
2
PP
PP
hop south 1 1 kt
You should print error message:
Error: Creature (hop south 1 1) has an invalid ability kt!
If there are multiple such errors, you only need to print out the first invalid ability of the first
creature that has invalid abilities. Note that it is allowed to have multiple characters of the same
valid ability. You just ignore the redundant ones. For example, creature description
hop south 1 1 f a f
has two ‘f’s, but it is legal.
15. Check whether each square in the grid is occupied by at most one creature. If any square is
occupied by more than one creature, print the following error message:
Error: Creature (<SP1> <DIR1> <R> <C>) overlaps with creature (<SP2> <DIR2> <R> <C>)!
where (<R> <C>) identifies the square which is occupied by more than one creature, the first
four-tuple (<SP1> <DIR1> <R> <C>) identifies the second creature in order that
occupies the square, and the second four-tuple (<SP2> <DIR2> <R> <C>) identifies the
first creature in order that occupies the square. Once you find two creatures occupying the
same square, you issue the above error message and then terminate the program.
16. Check whether a creature that cannot fly is not in a lake square. If a creature that cannot fly is
in a lake square, print the following error message:
Error: Creature (<SP> <DIR> <R> <C>) is in a lake square!
The creature cannot fly!
where the four-tuple (<SP> <DIR> <R> <C>) identifies the creature that cannot fly but is
in a lake square. If there are multiple such creatures, you only need to print out the first one and
then terminate the program.
Since you may implement the error checking in different order and in the case that there is
more than one error, the first error message printed out may be different. Therefore, we
will only test your error checking using test cases containing just one error.
VII. Simulation Output
Once all of the above error checkings on the initial state of the creature world are passed, you
can start simulating the creature world. You should print to the standard output the simulation
information, either in a verbose mode or in a concise mode, depending on whether an
additional argument “v” or “verbose” is provided by the user.
In the verbose mode, you first print the initial state of the world. In doing so, you begin with
printing the string “Initial state” followed by a newline. Then you graphically show the
layout of the initial grid using just characters. Each square takes a four-character field in your
terminal. Adjacent squares on the same row are separated by one space. If a square in the grid is
not occupied by any creature, the field for that square is filled with FOUR “_”. If a square is
occupied by a creature, then the first two characters of the field for that square are the first two
letters of the name of the species the creature belongs to. (We assume that all the species names
contain at least two characters and no two species names have the identical first two characters.)
The third character in the field is a “_” and the fourth character is the first character of the
direction the creature faces, i.e., “e” for “east”, “s” for “south”, “w” for “west”, and “n” for
“north”.
For example, suppose a world file looks like
4
4
PPPP
PPPP
PPPP
PPPP
hop east 2 0
flytrap east 2 2
(Note that the above example is a trivial example, in which all the terrain squares are plain and
no creatures have special abilities. However, it is enough to illustrate the output format.)
Then the layout of the initial grid is printed as
____ ____ ____ ____
____ ____ ____ ____
ho_e ____ fl_e ____
____ ____ ____ ____
Note that there is a space at the end of each line.
After printing the initial layout, we begin the simulation from the first round to the last round
specified by the user. In the i-th simulation round, you first print “Round <i>” followed by a
newline. For example, in the first round, you should first print
Round 1
During each simulation round, you simulate the moves of all the creatures in turn. When starting
simulating a creature, you announce that this creature takes action by printing
Creature (<SPECIES> <DIR> <R> <C>) takes action:
followed by a newline. In the above output, the four-tuple (<SPECIES> <DIR> <R> <C>)
shows the state of the creature right before it takes the action, where <SPECIES> should be
replaced by the species the creature belongs to, <DIR> be replaced by the direction the creature
is facing, <R> be replaced by the row location of the creature, and <C> be replaced by the
column location of the creature.
After this, you print the sequence of instructions that the creature executes for its turn. This
sequence may include any number of if*** and go instructions and end with one of the hop, left,
right, and infect instruction. You should print the sequence of instructions the creature executes
in order, with one instruction per line. The output format for an instruction is:
Instruction <INSTR_NO>: <INSTR_NAME> [GOTO_STEP]
where <INSTR_NO> should be replaced by the number of that instruction in the program (the
number starts from 1), <INSTR_NAME> should be replaced by the name of the instruction, and
[GOTO_STEP] is the number in an if*** or a go instruction and is optional.
After printing the last instruction of the creature under consideration, you should print the
updated layout of the grid, using the same rule as you print the initial layout.
In the special case where the creature is in a hill square and stays idle for the current round, then
nothing should be printed out for this creature, including the layout of the grid.
Now let’s look at an example. Suppose that the program for the species hop is
hop
go 1
and the program for the species flytrap is
ifenemy 4 If there is an enemy, go to step 4.
left If no enemy, turn left.
go 1
infect
go 1
Then, given the following world file
4
4
PPPP
PPPP
PPPP
PPPP
hop east 2 0
flytrap east 2 2
the simulation information for the first round is printed as
Round 1
Creature (hop east 2 0) takes action:
Instruction 1: hop
____ ____ ____ ____
____ ____ ____ ____
____ ho_e fl_e ____
____ ____ ____ ____
Creature (flytrap east 2 2) takes action:
Instruction 1: ifenemy 4
Instruction 2: left
____ ____ ____ ____
____ ____ ____ ____
____ ho_e fl_n ____
____ ____ ____ ____
The simulation information for the second round is printed as
Round 2
Creature (hop east 2 1) takes action:
Instruction 2: go 1
Instruction 1: hop
____ ____ ____ ____
____ ____ ____ ____
____ ho_e fl_n ____
____ ____ ____ ____
Creature (flytrap north 2 2) takes action:
Instruction 3: go 1
Instruction 1: ifenemy 4
Instruction 2: left
____ ____ ____ ____
____ ____ ____ ____
____ ho_e fl_w ____
____ ____ ____ ____
In the concise mode, you print the initial state of the world in the same way as in the verbose
mode. When printing the simulation information for the i-th round, you first print “Round
<i>” followed by the newline. Then you print the final action of each creature in turn, with one
creature per line. The format is:
Creature (<SPECIES> <DIR> <R> <C>) takes action: <LAST_INSTR>
Same as in the verbose mode, the four-tuple (<SPECIES> <DIR> <R> <C>) shows the
state of the creature right before it takes the action. <LAST_INSTR> should be replaced by the
last instruction the creature executes for its turn, which is one of the hop, left, right, and infect
instruction. In the special case where the creature is in a hill square and stays idle for the current
round, then nothing should be printed out for this creature.
After printing the final actions for all the creatures, you print the updated layout at the end of
this round.
For the same world file as above:
4
4
PPPP
PPPP
PPPP
PPPP
hop east 2 0
flytrap east 2 2
In the concise mode, the simulation information for the first round is printed as
Round 1
Creature (hop east 2 0) takes action: hop
Creature (flytrap east 2 2) takes action: left
____ ____ ____ ____
____ ____ ____ ____
____ ho_e fl_n ____
____ ____ ____ ____
The simulation information for the second round is printed as
Round 2
Creature (hop east 2 1) takes action: hop
Creature (flytrap north 2 2) takes action: left
____ ____ ____ ____
____ ____ ____ ____
____ ho_e fl_w ____
____ ____ ____ ____
There are no blank lines in the output for both the verbose and concise mode.
VIII. Source Code Files and Compiling
There is a source code file located in the Project-3-Related-Files.zip on Canvas:
world_type.h: The header file which defines a number of types for you to use.
You should copy this file into your working directory. DO NOT modify it!
You need to write three other source code files. The first file is named as simulation.h,
which contains the declarations for all the functions you write, just like the p2.h in our project
two. The second file is named as simulation.cpp, which contains all the implementations of
those functions declared in the simulation.h. The third file is named as p3.cpp, which
contains only the main function.
IX. Implementation Requirements and Restrictions
1. In writing your code, you may use the following standard header files: <iostream>,
<fstream>, <sstream>, <iomanip>, <string>, <cstdlib>, and <cassert>. No
other header files can be included.
2. You may not define any global variables yourself. You can only use the global constant ints
and string arrays defined in world_type.h.
3. Pass large structs by reference rather than value. Where appropriate, pass const references /
pointers-to-const. Do not pass lots of little arguments when you can pass an appropriate, larger
4. All required output should be sent to the standard output stream; none to the standard error
stream.
5. You should strive not to duplicate identical or nearly‐identical code, and instead collect such
code into a single function that can be called from various places. Each function should do a
single job, though the definition of “job” is obviously open to interpretation. Most students write
too few functions that are too large.
X. Hints and Tips
1. This project will take you longer than project three did, so start early!
2. Do this project in stages. First, be able to read the species summary file. Second, be able to
read the programs for all the species. Third, be able to read the world file. Write some diagnostic
code that can print out the species summary, the program for each species, and the creatures, to
make sure that you are reading them correctly. Implement the error checking and test it with
different illegal inputs. Once you can read the structures in, implement the simple moves such as
left and right. Once you have that working, implement moves such as hop and infect. Finally,
implement if*** and go instructions.
3. Take advantage of the fact that enumerations are sequentially numbered from 0 to N‐1.
4. Use the right methods of input file stream to read file. In some cases, you may first use the
getline() function to read the entire line of a file and then use an input string stream to
extract the content from that line.
5. The hop instruction will only cause the creature to move forward when the square it is facing
is empty. If moving forward would put the creature outside the boundaries of the grid, would
cause the creature that cannot fly to land in a “lake” square, or would cause the creature to land
on top of another creature, the hop instruction does nothing. However, although the hop action is
not executed successfully, you should update the program counter so that it points to the next
instruction after this hop instruction. The similar situation also applies to the infect instruction. If
there is no enemy to infect, the infect operation does nothing. However, you should update the
program counter to its next instruction.
6. As a hint, you probably need to write the following eight functions or some variations of them.
However, these are not the only functions you have to write. You probably need to write more
functions for different jobs.
bool initWorld(world_t &world, const string &speciesFile,
const string &worldFile);
// MODIFIES: world
//
// EFFECTS: Initialize “world” given the species summary file
// “speciesFile” and the world description file
// “worldFile”. This initializes all the components of
// “world”. Returns true if initialization is successful.
void simulateCreature(creature_t &creature, grid_t &grid, bool
verbose);
// REQUIRES: creature is inside the grid.
//
// MODIFIES: creature, grid, cout.
//
// EFFECTS: Simulate one turn of “creature” and update the creature,
// the infected creature, and the grid if necessary.
// The creature programID is always updated. The function
// also prints to the stdout the procedure. If verbose is
void printGrid(const grid_t &grid);
// MODIFIES: cout.
//
// EFFECTS: print a grid representation of the creature world.
// EFFECTS: Returns a point that results from moving one square
// in the direction “dir” from the point “pt”.
direction_t leftFrom(direction_t dir);
// EFFECTS: Returns the direction that results from turning
// left from the given direction “dir”.
direction_t rightFrom(direction_t dir);
// EFFECTS: Returns the direction that results from turning
// right from the given direction “dir”.
instruction_t getInstruction(const creature_t &creature);
// EFFECTS: Returns the current instruction of “creature”.
creature_t *getCreature(const grid_t &grid, point_t location);
// REQUIRES: location is inside the grid.
//
// EFFECTS: Returns a pointer to the creature at “location” in “grid”.
XI. Testing
We provide you with a few test cases in the directory called tests, which can be found inside
Project-3-Related-Files.zip on Canvas.
Inside the tests directory, there is an example species summary file called species and two
subdirectories called creatures and world-tests. The creatures directory contains a
number of species program files. The world-tests directory contains five world files and the
files recording the correct outputs.
The first world file is called outside-world, which describes an illegal world with one
creature located outside the boundary of the grid.
To run this test case, type the following commands (Note: suppose the name of the compiled
program is p3):
./p3 species world-tests/outside-world 5 > outside-world.out
Then the output of your program is redirected to a file named outside-world.out. The
correct output is recorded in the file outside-world.answer in the directory worldtests. You can use the diff command to check whether the file outside-world.out is
The second world file is called overlap-world, which describes an illegal world with two
creatures located at the same square in the grid. You can run this test case using a similar
command as shown above and compare your output with the correct output recorded in the file
The next three world files world1, world2, and world3 are legal world files. You can run
these test cases in the similar way. The number of simulation rounds for world1, world2, and
world3 are 5, 20, and 40, respectively. For these test cases, we provide you with both the
verbose and the concise output files. The verbose output files are these files named as
*-verbose.answer and the concise output files are these files named as
These are the minimal amount of tests you should run to check your program. Those programs
that do not pass these tests are not likely to receive much credit. You should also write other
different test cases yourself to test your program extensively. In doing so, you need to write your
own legal/illegal species summary files, legal/illegal world files, and species program files.
Indeed, it will be very interesting to create new species yourself and observe what kind of
species will finally dominate the SIMPLE WORLD given different initial layout!
XII. Submitting and Due Date
You should submit your source code files simulation.h, simulation.cpp, and
p3.cpp. These files should be submitted as a tar file via the online judgment system. See
announcement from the TAs for details about submission. The due date is 11:59 pm on July 8th,
2018.