C – Passing Pointers to Functions2 min read

In C programming, just like we pass values of the variable as parameters in the function, we can also pass addresses as an argument in functions.

When we pass pointers in the function that means we pass the address of the variable instead of the value.

Syntax:

Let us see some examples.


1. Pass Addresses to Functions in C

Output: After execution following will be displayed.

The above program first takes the inputs from the user and passes the addresses of those inputs’ variable in the functions as an argument. The formal parameters (int *num1, int *num2) are the pointers that stores the addresses of those actual parameters.

The swapping process is done inside the function body. And lastly the value is displayed.


2. Passing Pointers to a Function in C

In the above program we saw how to pass the addresses and the actual arguments were the pointers to store that addresses. Here in the program below, we will pass the pointers directly to the function.

Output:

As you can see the ptr1 and ptr2 pointers stores the addresses of num1 and num2 and those addresses are passed as an actual parameter of the function. Inside the function, the sum result is returned. The code inside the function, *p1 + *p2 means that the actual value of the variable to which the pointer pointing is added.


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