How to swap lower byte (0-7) with the higher one (8-15) using C?

Question

e.g. Suppose I enter a string : Ram and Shyam likes Ramesh then the output should be Ramesh and Shyam likes Ram.
Here first word Ram is swapped with Ramesh .

Answer 1

Its very simple. You can achieve this by using bit wise operator.
Have a look.

Input :

int16_t num = 127;       // bit representation of 127 (0 0 0 0 0 0 0 0    0 1 1 1 1 1 1 1)
num = (num << 8 | num >> 8);       //This is what you need to do. This will swap the 0-7th bit to 8-15th bit

/*
    If you print the bit of "num" after  applying the left shift (<<) and right shift (>>) operation you will get the
    following output.
*/
 (0 1 1 1 1 1 1 1    0 0 0 0 0 0 0 0)

Here the program for that, (Tested):

#include <stdio.h>
#include <stdint.h>  // For int16_t

/*
     Function to print the bits of the given number. 
*/
void show_bit(int16_t n)
{
     int i = 16;
     while(i)
         (n >> (i-- - 1) & 1) ? printf("1 ") : printf("0 ");

     printf("\n");
}

int main()
{
    int16_t number = 127;  // You can change the number as per your requirement.

    printf("Before swaping the bits of (%d) :\n", number);
    show_bit(number);

    number = (number << 8 | number >> 8);

    printf("After swaping the bits of (%d) :\n", number);
    show_bit(number);

    return 0;
}

Output:

Before swaping the bits of (127) : 
0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 
After swaping the bits of (32512) :
0 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0