C program to swap two numbers using pointers

C program to swap two numbers using pointers - Source code

int main()
{
    int x,y,temp,*a,*b;
 
    printf("Enter the two numbers:\n");
    scanf("%d%d",&x,&y);
    printf("Before swapping:\n x = %d\n y = %d\n",x,y);
 
    a = &x;
    b = &y;
 
    temp = *b;
    *b = *a;
    *a = temp;
 
    printf("After swapping:\n x = %d\n y = %d\n",x,y);
    return 0;
}

Program Output

Case 1:

Enter the two numbers:
30
56
Before swapping:
 x = 30
 y = 56
After swapping:
 x = 56
 y = 30


Case 2 :

Enter the two numbers:
1
0
Before swapping:
 x = 1
 y = 0
After swapping:
 x = 0
 y = 1

Program Explanation

1. In the declaration part of the program, three integer variables x,y and temp are declared alongside with two integer pointer variables a and b.

2. After accepting two integers from the user using the scanf function, values of x and y are printed(before swapping).

3. Pointer a is assigned the address value of the variable x using the & operator. Similarly, the memory address of variable y is assigned to pointer b.

4. In the next statement, value of pointer b is stored in the temp variable using assignment operator. Now, we can assign the value of pointer a to b and value of pointer b (stored in variable temp) to a.

5. By swapping the memory addresses of the variables, their values automatically get swapped.