Interactive C program to Swap bits in 32 bit integer

/*
* Program to swap bit in given 32 bit Integer number
*/
#include<stdio.h>
int main()
{
int a;
int b1, b2;
printf("Enter numbers \n");
scanf("%d", &a);
printf("Enter bit numbers to be swapped\n");
scanf("%d%d", &b1, &b2);
if(b1 >=31 || b2>=31){
    printf("Invalid bit positions(valid are 0 - 31)\n");
    return 0;
}

if((a&(1<<b1)) && !(a&(1<<b2))){
    /* bit number b1 is set but b2 is not
     * to swap just unset b1 and set b2
     */
      a=a & ~(1<<b1);
      a=a | (1 << b2);
} else if(!(a&(1<<b1)) && (a&(1<<b2))){
       /* bit b1 is not set(zero) and bit b2 is set
        * so to swap set b1 and clear b2
        */
      a=a | (1<<b1);
      a=a & ~(1<<b2);
} else {
     /* given both bits are set/clear in number so nothing to be done*/
}

printf("Number after bit swap is %d\n", a);
return 0;
}

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