C program to swap two numbers using Call by value and Call by reference parameter passing techniques

Call by value

Program :

#include<stdio.h>

void swp(int a,int b);

main()

{

int a,b,temp;

clrscr();

printf("enter the values of a and b\n");

scanf("%d%d",&a,&b);

printf("\nvalues before calling swap function\n a:%d, b:%d\n",a,b);

swp(a,b);

getch();

}

void swp( int num1,int num2)

{

int temp;

printf("\ninside the function swap before swaping\n");

printf("num1:%d, num2:%d\n",num1,num2);

temp=num1;

num1=num2;

num2=temp;

printf("\ninside the function swap after swaping\nnum1:%d, num2:%d\n",num1,num2);

printf("\nvalues after calling swap function\n a:%d, b:%d\n",num1,num2);

}

Output:

Enter the values of a and b
55
66
values before calling swap function
 a:55, b:66
inside the function swap before swaping
num1:55, num2:66
inside the function swap after swaping
num1:66, num2:55
values after calling swap function
 a:66, b:55


Enter the values of a and b
23
32
values before calling swap function
 a:23, b:32
inside the function swap before swaping
num1:23, num2:32
inside the function swap after swaping
num1:32, num2:23
values after calling swap function
 a:32, b:23


Call by reference:

Program: 

#include<stdio.h>
void swap (int *a,int *b);
int main()
{
int a,b;
clrscr();
printf("Enter two numbers\n");
scanf("%d%d",&a,&b);
printf("Values before calling swap function\n");
printf("a:%d\t b:%d\n",a,b);
swap (&a,&b);
printf("Values after calling swap\n");
printf("a:%d\t b:%d\n",a,b);
getch();
}
void swap(int *pa,int *pb)
{
int temp,a,b;
printf("Inside the function swap  before swapping\n");
printf("a:%d\t b:%d\n",*pa,*pb);
temp=*pa;
*pa=*pb;
*pb=temp;
printf("Inside the function swap  after swapping\n");
printf("a:%d\t b:%d\n",*pa,*pb);
}


Output:

Enter two numbers
55
66
Values before calling swap function
a:55     b:66
Inside the function swap before swapping
a:55     b:66
Inside the function swap after swapping
a:66     b:55
Values after calling swap 
a:66     b:55


Enter two numbers
22
33
Values before calling swap function
a:22     b:33
Inside the function swap before swapping
a:22     b:33
Inside the function swap after swapping
a:33     b:22
Values after calling swap
a:33     b:22