Pass Pointers to Functions in C

How to write a C Program to pass Pointers to Functions?. Or How the Pointers to Functions in C programming work with a practical example.

Pass Pointers to Functions in C Example

In this Pass Pointers to Functions program, we created a function that accepts two integer variables and swaps those two variables. I suggest you refer to the C Program to Swap two numbers article to understand the logic.

Like any other variable, you can pass the pointer as a function argument. I suggest you refer to the C Call By Value and Call by Reference and C Pointers article from the C Tutorial page to understand the function arguments and pointers.

#include<stdio.h>
 
void Swap(int *x, int *y)
{
    int Temp;
    Temp = *x;
    *x = *y;
    *y = Temp;
}

int main()
{
    int a, b;
    
    printf ("Please Enter 2 Integer Values :  ");
    scanf("%d %d", &a, &b);
    
    printf("\nBefore Swapping  A = %d and B = %d", a, b);
    
    Swap(&a, &b);
    
    printf(" \nAfter Swapping   A = %d and B = %d \n", a, b);
}

TIP: Please refer to the functions in C, types of UDFs in C, recursion in C, and pass array to a function articles.

Pass Pointers to Functions Example 2

In this Pass Pointers to Functions program, we created a function that accepts the array pointer and its size. Please refer to the C program to find the Sum of All Elements in an Array article to know the logic.

Within the main Pass Pointers to Functions program, we used a for loop to iterate over the array. Next, pass the user given value to an array. Next, we pass an array to a function. Please refer to the for loop in C and the array in C articles.

#include<stdio.h>
 
int SumofArrNumbers(int *arr, int Size)
{
    int sum = 0;
    for(int i = 0; i < Size; i++)
    {
        sum = sum + arr[i];
    }
    return sum;
}
int main()
{
    int i, Addition, Size, a[10];
    printf("Please Enter the Size of an Array : ");
    scanf("%d", &Size);
    
    printf("\nPlease Enter Array Elements  :  ");
    for(i = 0; i < Size; i++)
    {
        scanf("%d", &a[i]);
    }
    
    Addition = SumofArrNumbers(a, Size);
    printf("Sum of Elements in this Array = %d \n", Addition);
    return 0;
}

Please Enter the Size of an Array : 7

Please Enter Array Elements  :  10 20 200 30 500 40 50
Sum of Elements in this Array = 850