Passing array to function in C programming with example

Array can be passed as an argument to a function – This tutorial covers few examples to demonstrate how to do it.

Call by value method –

In this method of calling a function, the actual arguments gets copied into formal arguments. In this example actual argument(or parameter) is arr[x] and formal parameter is ch.

#include <stdio.h>
disp( char ch)
{
   printf("%c ", ch);
}
int main()
{
   char arr[] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'I', 'j'};
   for (int x=0; x<=10; x++)
   {
       /* I’m passing each element one by one using subscript*/
       disp (arr[x]);
   }

   return 0;
}

Output:

a b c d e f g h i j

Call by reference method: Using pointers

In this method, address of actual parameters gets copies into formal parameters. In below example, we are passing the address of array’s element as an argument to the function,  instead of their values. We have to use pointers for this.

#include <stdio.h>
disp( int *num)
{
    printf("%d ", *num);
}

int main()
{
     int arr[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 0};
     for (int i=0; i<=10; i++)
     {
         /* I’m passing element’s address*/
         disp (&arr[i]);
     }

     return 0;
}

Output:

1 2 3 4 5 6 7 8 9 0

In the above example I have used pointer in function’s argument, which has been used to accept the addresses of elements and later I have used star(*) operator to print the values stored at their memory location.

How to pass an entire array to a function argument?

Till here, we have learnt how to pass individual array’s element to a function. Now we will see how to pass an entire array to a function. The below code demonstrate the same –

#include <stdio.h>
myfuncn( int *var1, int var2)
{
    for(int x=0; x<var2; x++)
    {
        printf("Value of var_arr[%d] is: %d \n", x, *var1);
        /*increment pointer for next element fetch*/
        var1++;
    }
}

int main()
{
     int var_arr[] = {11, 22, 33, 44, 55, 66, 77};
     myfuncn(&var_arr, 7);
     return 0;
}

Output:

Value of var_arr[0] is: 11
Value of var_arr[1] is: 22
Value of var_arr[2] is: 33
Value of var_arr[3] is: 44
Value of var_arr[4] is: 55
Value of var_arr[5] is: 66
Value of var_arr[6] is: 77