How to return a Pointer from a Function in C
Pointers in C programming language is a variable which is used to store the memory address of another variable. We can pass pointers to the function as well as return pointer from a function. But it is not recommended to return the address of a local variable outside the function as it goes out of scope after function returns.
Program 1: The below program will give segmentation fault since 'A' was local to the function:// C program to illustrate the concept of
// returning pointer from a function
#include <stdio.h>
// Function returning pointer
int* fun()
{
int A = 10;
return (&A);
}
// Driver Code
int main()
{
// Declare a pointer
int* p;
// Function call
p = fun();
printf("%p\n", p);
printf("%d\n", *p);
return 0;
}
Explanation:
The main reason behind this scenario is that compiler always make a stack for a function call. As soon as the function exits the function stack also gets removed which causes the local variables of functions goes out of scope.
Static Variables have a property of preserving their value even after they are out of their scope. So to execute the concept of returning a pointer from function in C you must define the local variable as a static variable.
Program 2:// C program to illustrate the concept of
// returning pointer from a function
#include <stdio.h>
// Function that returns pointer
int* fun()
{
// Declare a static integer
static int A = 10;
return (&A);
}
// Driver Code
int main()
{
// Declare a pointer
int* p;
// Function call
p = fun();
// Print Address
printf("%p\n", p);
// Print value at the above address
printf("%d\n", *p);
return 0;
}
0x601038 10
