Week 7 Code Examples

#include <stdio.h>

int main(void) {
    int* number_ptr;
    char *letter_ptr;
    int number = 6;
    char letter = 'c';
    number_ptr = &number;
    letter_ptr = &letter;
    printf("number is %d and is stored at %p\n", number, number_ptr);
    printf("letter is %c and is stored at %p\n", letter, letter_ptr);
    return 0;
}

#include <stdio.h>

int main(void) {
    int number = 6;
    int *number_ptr = &number;
    printf("number_ptr deferences to %d, and is stored at %p\n", *number_ptr, number_ptr);
    return 0;
}

#include <stdio.h>
#include <stdlib.h>

struct node {
    int data;
    struct node *next;
};

struct node *create_node(int data) {
    struct node *new_node = malloc(sizeof(struct node));
    new_node->data = data;
    new_node->next = NULL;
    return new_node;
}

void free_linked_list(struct node *head) {
    struct node *current = head;
    struct node *prev = head;
    while (current != NULL) {
        current = current->next;
        free(prev);
        prev = current;
    }
}

void print_linked_list(struct node *head) {
    struct node *current = head;
    while (current != NULL) {
        printf("%d->", current->data);
        current = current->next;
    }
    printf("X\n");
    return;
}

struct node *insert_at_beginning(struct node *node_to_insert, struct node *head) {
    if (head == NULL) {
        head = node_to_insert;
        return head;
    }
    node_to_insert->next = head;
    head = node_to_insert;
    return head;
}

struct node *insert_at_end(struct node *node_to_insert, struct node *head) {
    struct node *current = head;
    while (current->next != NULL) {
        current = current->next;
    }
    current->next = node_to_insert;
    return head;
}

struct node *insert_after_value(struct node *node_to_insert, struct node *head, int value) {
    struct node *current = head;
    if (head == NULL) {
        printf("List is empty, cannot insert after value\n");
        return head;
    }
    while (current != NULL) {
        if (current->data == value) {
            node_to_insert->next = current->next;
            current->next = node_to_insert;
            return head;
        }
        current = current->next;
    }
    printf("Entire list traversed, %d not found, cannot insert\n", value);
    return head;
}

struct node *insert_before_value(struct node *node_to_insert, struct node *head, int value) {
    if (head == NULL) {
        printf("List is empty, cannot insert after value\n");
        return head;
    }
    struct node *current = head;
    while (current != NULL) {
        if (current->next->data == value) {
            node_to_insert->next = current->next;
            current->next = node_to_insert;
            return head;
        }
        current = current->next;
    }
    printf("Entire list traversed, %d not found, cannot insert\n", value);
    return head;
}

int main(void) {
    struct node *my_node = create_node(5);
    struct node *second_node = create_node(67);
    struct node *third_node = create_node(100);
    struct node *fourth_node = create_node(151);
    struct node *fifth_node = create_node(1000);
    struct node *sixth_node = create_node(17);
    struct node *seventh_node = create_node(180);
    struct node *head = insert_at_beginning(my_node, NULL);
    head = insert_at_beginning(second_node, head);
    head = insert_at_beginning(third_node, head);
    head = insert_at_end(fourth_node, head);
    head = insert_at_end(fifth_node, head);
    head = insert_after_value(sixth_node, head, 5);
    head = insert_before_value(seventh_node, head, 5);
    print_linked_list(head);
    free_linked_list(head);
    return 0;
}

#include <stdio.h>

int sum(void) {
    return x + y;
}

int main(void) {
    int x = 12;
    int y = 13;
    sum();
    return 0;
}

#include <stdio.h>
#include <stdlib.h>

int main(void) {
    int x = 10;
    int *ptr = malloc(x * sizeof(int));
    printf("%p\n", ptr);
    return 0;
}

#include <stdio.h>

#include "maths.h"

int main(void) {

    int area = rect_area();

    printf("The area is: %d\n", area);

    double c_area = circle_area();
    
    printf("The area is: %lf\n", c_area);

    double t_area = triangle_area();
    printf("The area is: %lf\n", t_area);
    
    return 0;
}

#include <stdio.h>
#include "maths.h"

int rect_area(void) {
    int height;
    int width;

    int area;

    printf("Enter the width and height of the rectangle: ");
    scanf("%d %d", &height, &width);

    area = height * width;

    return area;
}

double circle_area(void) {
    double radius;
    printf("Enter the radius of the circle: ");

    scanf("%lf", &radius);

    double area = PI * (radius * radius);

    return area;
}

double triangle_area(void) {
    int base;
    int height;
    printf("Enter the height of your triangle: ");
    scanf("%d", &height);
    printf("Enter the base of your triangle: ");
    scanf("%d", &base);
    double area = 0.5 * base * height;
    return area;
}

#include <stdio.h>

#define PI 3.141592653589

// This function calculates the area of a rectangle
// it scans in a height and width and returns the result
int rect_area(void);


// THis function calculates teh area of a circle
// in scans in a radius and resturns the result
double circle_area(void);

// This function calculates the area of a triangle
// it scans in a base and height and returns the result
double triangle_area(void);

#include <stdio.h>

int main(void) {
    int box = 12;
    int *box_add = &box;
    int area = *box_add * box;
    printf("%d\n", area);
    return 0;
}

#include <stdio.h>

int sum(int x, int y) {
    return x+y;
}

int main(void) {
    int x;
    int *x_ptr;
    x = 17;
    x_ptr = &x;
    x = 20;
    printf("x * 12 = %d", *x_ptr * 12);
    int number4 = sum(12, 13);
    return 0;
}

#include <stdio.h>

int main(void) {

    int array[10] = {0};

    // Display the size of various data types and variables.
    printf("The size of an int is %lu bytes\n", sizeof(int));
    printf("The size of an array of int is %lu bytes\n", sizeof(array));
    printf("The size of 10 ints is %lu bytes\n", 10 * sizeof(int));
    printf("The size of a double is %lu bytes\n", sizeof(double));
    printf("The size of a char is %lu bytes\n", sizeof(char));

    return 0;
}

#include <stdio.h>

struct movie {
    int runtime;
    int stars;
};

int main(void) {
    struct movie ht;
    struct movie *httyd = &ht;
    (*httyd).runtime = 120;
    (*httyd).stars = 5;
    printf("How to Train Your Dragon is %d minutes and a rating of %d stars\n", httyd->runtime, httyd->stars);
    return 0;
}

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

#define MAX 35

// 1. Define the struct
struct pet {
    char name[MAX];
    char species[MAX];
    int age;
    double weight;
};

int main(void) {
    struct pet my_pet;

    struct pet *pet_ptr = &my_pet;

    strcpy(pet_ptr->name, "Buddy");
    strcpy(pet_ptr->species, "Dog");
    pet_ptr->age = 3;
    pet_ptr->weight = 12.50;

    printf("--- Pet Record ---\n");
    printf("Name:    %s\n", pet_ptr->name);
    printf("Species: %s\n", pet_ptr->species);
    printf("Age:     %d years old\n", pet_ptr->age);
    printf("Weight:  %.2lf kg\n", pet_ptr->weight);

    return 0;
}

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

#define MAX 35

// 1. Define the struct
struct pet {
    char name[MAX];
    char species[MAX]; // "Dog" or "Cat" or ???
    int age;
    double weight;
};

int main(void) {
    struct pet my_pet;

    struct pet *pet_ptr = &my_pet;

    strcpy((*pet_ptr).name, "Buddy");
    strcpy((*pet_ptr).species, "Dog");
    (*pet_ptr).age = 3;
    (*pet_ptr).weight = 12.50;

    printf("--- Pet Record ---\n");
    printf("Name:    %s\n", (*pet_ptr).name);
    printf("Species: %s\n", (*pet_ptr).species);
    printf("Age:     %d years old\n", (*pet_ptr).age);
    printf("Weight:  %.2lf kg\n", (*pet_ptr).weight);

    return 0;
}

#include <stdio.h>

void swapsies(int* x, int* y) {
    int temp = *x;
    *x = *y;
    *y = temp;
    return;
}

int main(void) {
    int x = 12;
    int y = 13;
    printf("x = %d and y = %d\n", x, y);
    swapsies(&x, &y);
    printf("x = %d and y = %d\n", x, y);
    return 0;
}

#include <stdio.h>

// malloc() and free() are functions in the <stdlib.h> library

#include <stdlib.h>

void read_array(int *numbers, int size);
void reverse_array(int *numbers, int size);

int main (void) {
    int size;
    printf("How many numbers would you like to scan: ");
    scanf("%d", &size);

    // Allocate some memory space for my array and return a pointer
    // to the first element
    int *numbers = malloc(size * sizeof(int));

    // Check if there is actually enough space to allocate
    // memory, exit the program if there is not enough memory
    // to allocate.

    if (numbers == NULL) {
        printf("Malloc failed, not enough space to allocate memomry\n");
        return 1;
    }

    // Perform some functions here
    read_array(numbers, size);
    reverse_array(numbers, size);

    // Free the allocated memory
    // In this case, it would happen on program exit anyway
    free(numbers);

    return 0;
}

void read_array(int *numbers, int size) {
    for (int i = 0; i < size; i++) {
        printf("Enter number %d: ", i + 1);
        scanf("%d", &numbers[i]);
    }
}

void reverse_array(int *numbers, int size) {
    int start = 0;
    int end = size - 1;

    while (start < end) {
        int temp = numbers[start];
        numbers[start] = numbers[end];
        numbers[end] = temp;
        start++;
        end--;
    }

    printf("Reversed array: ");
    for (int i = 0; i < size; i++) {
        printf("%d ", numbers[i]);
    }
    printf("\n");
}