Functions

    #include <stdio.h>
    
    // function prototypes
    int my_addition(int a, int b);
    int my_multiplication(int c, int d);
    int my_square(int n);
    void my_print(int x, int y, int z);
    
    int main()
    {
    
        int x = 1;
        int y = 2;
        
        // call the user-defined function my_addition(...)
        int sum = my_addition(x, y);
    
        // call the user-defined function my_multiplication(...)
        int product = my_multiplication(x, y);
    
        // use the user-defined function my_square(...)
        int square = my_square(x);
    
        // use the user-defined procedure my_print(...)
        my_print(sum, product, square);
    
        return 0;
    }
    
    // A function
    int my_addition(int a, int b)
    {
        return a + b;
    }
    
    // Another function
    int my_multiplication(int c, int d)
    {
        return c * d;
    }
    
    // Yet another function which calls some function
    int my_square(int n)
    {
        return my_multiplication(n, n);
    }
    
    // A procedure
    void my_print(int x, int y, int z)
    {
        printf("Now behold my super printing function!\n");
        printf("x = %d, y = %d, z = %d\n", x, y, z);
        printf("As you can see, it is completely useless,\n");
        printf("without printf it can do nothing!\n");
    }