When, argument is passed using Pointer, address of the memory location is passed instead of value.
Example of Pointer And Functions
Program to swap two number using call by reference.
/* C Program to swap two numbers using pointers and function. */
#include
void swap(int *a,int *b);
int main(){
int num1=5,num2=10;
swap(&num1,&num2); /* address of num1 and num2 is passed to swap function */
printf("Number1 = %d\n",num1);
printf("Number2 = %d",num2);
return 0;
}
void swap(int *a,int *b){ /* pointer a and b points to address of num1 and num2 respectively */
int temp;
temp=*a;
*a=*b;
*b=temp;
}
Output
Number1 = 10
Number2 = 5
Explanation
The address of memory location num1 and num2are passed to function and the pointers *a and *baccept those values. So, the pointer a and b points to address of num1 and num2 respectively. When, the value of pointer are changed, the value in memory location also changed correspondingly. Hence, change made to *aand *b was reflected in num1 and num2in main function.
This technique is known as call by reference in C programming.
