Week 4 Code Examples

2D_arrays/2D_array.c

#include <stdio.h>
#define ROWS 2
#define COLS 3

void print_grid(int grid[ROWS][COLS]);
void scan_grid(int grid[ROWS][COLS]);
int sum_grid(int grid[ROWS][COLS]);

void print_row_sums(int grid[ROWS][COLS]);
void print_col_sums(int grid[ROWS][COLS]);
void copy_array(int grid[ROWS][COLS], int grid_copy[ROWS][COLS]);

//Create a new grid
//copy grid
//Do some for loops

int main(void) {
    int grid[ROWS][COLS] =  {{3, 5, 1},
                            {2, 4, 9}};
    
    int grid2[ROWS][COLS];
    
    copy_array(grid, grid2);

    print_grid(grid); 
    print_grid(grid2);

    //Make a copy

    //Turn it into a function
    return 0;
}

void copy_array(int grid[ROWS][COLS], int grid_copy[ROWS][COLS]){
    int row = 0;
    while (row < ROWS) {
        int col = 0;
        while (col < COLS) {
            grid_copy[row][col] = grid[row][col];
            col++;
        }
        row++;
    }
}

void print_grid(int grid[ROWS][COLS]) {
    printf("Grid\n");
    int row = 0;
    while (row < ROWS) {
        int col = 0;
        while (col < COLS) {
            printf("%d ", grid[row][col]);
            col++;
        }
        printf("\n");
        row++;   
    }
}

void scan_grid(int grid[ROWS][COLS]) {
    printf("Please enter data\n");
    printf("Grid\n");
    int row = 0;
    while (row < ROWS) {
        int col = 0;
        while (col < COLS) {
            scanf("%d", &grid[row][col]);
            col++;
        }
        row++;   
    }
}

int sum_grid(int grid[ROWS][COLS]) {
    int sum = 0;
    int row = 0;
    
    while (row < ROWS) {
        int col = 0; 
        while (col < COLS) {
            sum = sum + grid[row][col];
            col++;
        }
        row++;
    }

    return sum;
}

void print_row_sums(int grid[ROWS][COLS]) {
    int row = 0;
    
    while (row < ROWS) {
        int col = 0; 
        int sum = 0;
        while (col < COLS) {
            sum = sum + grid[row][col];
            col++;
        }
        printf("Sum of row %d is %d\n", row, sum);
        row++;
    }
}

void print_col_sums(int grid[ROWS][COLS]) {
     int col = 0;
    
    while (col < COLS) {
        int row = 0; 
        int sum = 0;
        while (row < ROWS) {
            sum = sum + grid[row][col];
            row++;
        }
        printf("Sum of col %d is %d\n", col, sum);
        col++;
    }
}
 
 /*
  printf("The sum was %d\n", sum_grid(grid));
    print_row_sums(grid);
    print_col_sums(grid);
    */

//convert to for loops?

// int row;
//     int col;
//     printf("Enter a row and col: ");
//     scanf("%d %d", &row, &col);
//     printf("Element was %d\n", grid[row][col]);

//  //scan_grid(grid);
// printf("The sum is %d\n", sum_grid(grid));
//     print_row_sums(grid);
//     print_col_sums(grid);

2D_arrays/diagonals.c

#include <stdio.h>
#define SIZE 4

int sum_diagonal_top_left(int grid[SIZE][SIZE]);
int sum_diagonal_top_right(int grid[SIZE][SIZE]);

int main(void) {
    int grid[SIZE][SIZE] = {{3, 5, 1, 2},
                            {2, 4, 9, 8},
                            {6, 0, 2, 7},
                            {4, 1, 6, 5}};

    printf("The sum diagonal top left %d\n", sum_diagonal_top_left(grid));
    printf("The sum diagonal top right %d\n", sum_diagonal_top_right(grid));
   
    return 0;
}

int sum_diagonal_top_left(int grid[SIZE][SIZE]){
    int index = 0;
    int sum = 0;
    while (index < SIZE) {
        sum = sum + grid[index][index];
        index++;
    }
    return sum;
}
 
// int sum_diagonal_top_left(int grid[SIZE][SIZE]){
//     int sum = 0;
//     int row = 0;
    
//     while (row < SIZE) {
//         int col = 0; 
//         while (col < SIZE) {
//             if (row == col) {
//                 sum = sum + grid[row][col];
//             }
//             col++;
//         }
//         row++;
//     }
//     return sum;
// }


// int sum_diagonal_top_right(int grid[SIZE][SIZE]){
//     int sum = 0;
//     int row = 0;
    
//     while (row < SIZE) {
//         int col = 0; 
//         while (col < SIZE) {
//             if (row + col == SIZE - 1) {
//                 sum = sum + grid[row][col];
//             }
//             col++;
//         }
//         row++;
//     }
//     return sum;
// }

int sum_diagonal_top_right(int grid[SIZE][SIZE]){
    
    int sum = 0;
    for (int index = 0; index < SIZE;  index++) {
        sum = sum + grid[index][SIZE - index - 1];
    }
    return sum;
}

array_of_strings/array_of_strings.c

// An example of an array of strings
// This assumes we have at most 20 9 letter words

#include <stdio.h>
#include <string.h>

#define MAX_STRINGS 20
#define MAX_LEN 10

//  0  1  2  3  4  5  6  7  8  9
//0 h  a  t \0 
//1 c  a  k  e  \0 
//2 t  e  a \0
//3 s  u  n \0
//4 \0
//5 \0
//etc


void print_text(char text[MAX_STRINGS][MAX_LEN], int max_lines);

int main(void){
    char text[MAX_STRINGS][MAX_LEN] = {"hat", "cake", "tea"};
    int num_strings = 3;
    // Print one string
    printf("%s\n", text[2]);    
    // Print one character
    printf("%c\n", text[1][2]);

    printf("Printing out text\n");
    print_text(text, num_strings);

    strcpy(text[3], "sun");
    num_strings++;
    
    printf("Printing out text\n");
    print_text(text, num_strings);

    return 0;
}

void print_text(char data[MAX_STRINGS][MAX_LEN], int size){
    for (int i = 0; i < size; i++) {
        printf("%s\n", data[i]);
    }
}

arrays/numbers_functions.c

// Week 4 Lecture recap example
// Using arrays with functions

#include <stdio.h>
#define DATA_SIZE 6


void print_data(int size, int data[]);
void read_data(int size, int data[]);

// TODO
void print_odd_data(int size, int data[]);
int find_maximum(int size, int data[]);

int main(void) {
    int data[DATA_SIZE] = {4, 6, 7, -3, 9, 2};
    //int data[DATA_SIZE];
    //read_data(DATA_SIZE, data);
    print_data(DATA_SIZE, data);
    print_odd_data(DATA_SIZE, data);
    printf("The max is %d\n", find_maximum(DATA_SIZE, data));
    return 0;
}

int find_maximum(int size, int data[]) {
    int max = data[0];
    int i = 0;
    while (i < size) {
        if (data[i] > max) {
            max = data[i];
        }
        i++;
    }

    return max;
}

// WHY CAN WE MODIFY DATA IN THE ARRAY FROM THE FUNCTION?
void read_data(int size, int data[]) {
    printf("Enter data: "); 
    int i = 0;
    while (i < size) {
        scanf("%d", &data[i]);
        i++;
    }
}

void print_data(int size, int data[]) {
    int i = 0;
    while (i < size) {
        printf("%d ", data[i]);
        i++;
    }
    printf("\n");
}

void print_odd_data(int size, int data[]) {
    int i = 0;
    while (i < size) {
        if (data[i] % 2 != 0) {    
            printf("%d ", data[i]);
        }
        i++;
    }
    printf("\n");
}

arrays/struct_array.c

// Week 4 Lecture 1 example
// Using arrays of structs

#include <stdio.h>
#define MAP_SIZE 5

struct coordinate {
    int x;
    int y;
};

void read_map(int size, struct coordinate map[]); 
void print_map(int size, struct coordinate map[]);
void move_x(int size, struct coordinate map[], int x_amount);

// Translate function

int main(void) {
    struct coordinate map[MAP_SIZE];
    read_map(MAP_SIZE, map);
    print_map(MAP_SIZE, map);
    move_x(MAP_SIZE, map, 10);
    print_map(MAP_SIZE, map);
    return 0;
}

void read_map(int size, struct coordinate map[]){
     int i = 0;
     printf("Enter data:");
     while (i < size) {
        scanf("%d %d", &map[i].x, &map[i].y);
        i++;
     }
}

void print_map(int size, struct coordinate map[]){
     int i = 0;
     while (i < size) {
        printf("(%d, %d) ", map[i].x, map[i].y);
        i++;
     } 
     printf("\n");
}

void move_x(int size, struct coordinate map[], int x_amount) {
    int i = 0;
    while (i < size){
        map[i].x = map[i].x + x_amount;
        i++;
    }
}

command_line_args/atoi_demo.c

// Week 5 pre-recorded lecture Part 2 code demo
// showing the use of atoi
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
    int sum = 0;
    for (int i = 1; i < argc; i++) {
        // atoi converts a string to an int
        // For example atoi("123") would return the int 123.
        sum = sum + atoi(argv[i]);
    }
    printf("%d is the sum of all command line args\n", sum);
    return 0;
}

command_line_args/command_line_args.c

// Week 5 pre-recorded lecture Part 2 code demo
// showing the use of command line arguments
// For example you can run this program like
// ./command_line_args "hello world" 5 BLAH
// 

#include <stdio.h>

int main(int argc, char *argv[]) {
    printf("There are %d command line arguments\n", argc);
   
    // argv[0] is always the program name
    printf("This program name is %s\n", argv[0]);

  
    // print out all arguments in the argv array
    for (int i = 1; i < argc; i++) {
        printf("Argument at index %d is %s\n", i, argv[i]);
         

    }
    return 0;
}

strings/read_strings.c

// Lecture example for COMP1511/1911 Week 4 Thursday
// Some simple examples demonstrating how strings work in C

#include <stdio.h>
#include <ctype.h>

#define MAX 20

void capitalise(char s[]);

int main(void) {
    char movie[MAX];

    printf("Enter your favourite movies: ");
    while (fgets(movie, MAX, stdin) != NULL) {
        capitalise(movie);
        printf("The movie: %s\n", movie);
    }
   

    return 0;
}

void capitalise(char s[]) {
    for (int i = 0; s[i] != '\0'; i++){
        s[i] = toupper(s[i]);
    }
}

 // Read in one string (try one that is too long)
    // Print it out

    // Read in many strings instead of 1
    // Capitalise each string

strings/simple_strings.c

// Lecture example for COMP1511/1911 Week 4 Thursday
// Some simple examples demonstrating how strings work in C 

#include <stdio.h>

#define MAX_LEN 100

void print_string(char s[]);

int main(void) {
    // What do these look like in memory
    char favourite_food[] = {'k', 'f', 'c', '\0'}; 
    char favourite_drink[] = "kombucha";
    char favourite_book[MAX_LEN] = "Folk of the Faraway Tree";

    // Can print out characters
    printf("%c\n",favourite_food[0]);
    printf("%c\n",favourite_drink[3]);

    // Can print out the whole string
    printf("%s\n", favourite_food);
    printf("%s\n", favourite_drink);
    printf("%s\n", favourite_book);
    
    favourite_drink[0] = 'Z';
    printf("%s\n", favourite_drink);
    
    favourite_drink[4] = '\0';
    printf("%s\n", favourite_drink);
    
    //favourite_food[3] = 'd';
    //printf("%s\n", favourite_food);
    
    //favourite_book = "Programming in C";

    //print_string(favourite_food);

    // How do you think we read them in?
    
    return 0;
}

// Our own version of printf("%s")
void print_string(char s[]) {
    
}

strings/string_functions.c

// Example of using string functions from string.h library
// strings can get a bit tricky and messy in C
// It is easy to overflow buffers or lose our '\0' characters!

#include <stdio.h>
#include <string.h>

#define MAX_LENGTH 100

int main(void) {
    // Declare an array to store a string
    char puppy[MAX_LENGTH] = "Boots";

    printf("%s\n", puppy);
 
    // Copy the string "Finn" into the word array
    // Make sure your array is big enough!!!
    
    strcpy(puppy, "Finn");
    printf("%s\n", puppy);

    // Find string length. It does NOT include '\0' in the length
    int len = strlen(puppy);
    printf("%s has length %d\n", puppy, len);


    // Declare an array to store a string
    char name[] = "Oscar";

    if (strcmp(name, "Oscar") == 0) {
        printf("Hi Oscar\n");
    } else {
        printf("You are not Oscar!\n");
    }

    if (strcmp(name, "Edgar") == 0) {
        printf("Hi Oscar\n");
    } else {
        printf("You are not Oscar!\n");
    }

    if (strcmp(name, "Edgar") < 0) {
        printf("Oscar Edgar\n");
    } else {
        printf("Edgar Oscar\n");
    }


    // Declare an array to store a string
    char name2[MAX_LENGTH];
    printf("\nType in a name: ");

    // Read in a string
    fgets(name2, MAX_LENGTH, stdin);

    // remove trailing new line character
    int name_len = strlen(name2);
    if (name2[name_len - 1] == '\n'){
        name2[name_len - 1] = '\0';
    }

    // Use strcmp to compare 2 strings
    if (strcmp("Oscar", name2) == 0) {
        printf("Yay Oscar!\n");
    }

    return 0;
}