Demonstrate the behaviour of bitshifting in C

bitshifting.c

#include <stdio.h>
/*** Output looks like the following ***/

/*  ******** Signed ********: */
/*  Bitshift right (>>=1)     */
/*  -128 in binary: 10000000  */
/*   -64 in binary: xxxxxxxx  */
/*                            */
/*  Bitshift right (>>=1)     */
/*    64 in binary: 01000000  */
/*    32 in binary: xxxxxxxx  */
/*                            */
/*  Bitshift left (<<=1)      */
/*     1 in binary: 00000001  */
/*     2 in binary: xxxxxxxx  */
/*                            */
/*                            */
/*  ******* Unsigned *******: */
/*  Bitshift right (>>=1)     */
/*   128 in binary: 10000000  */
/*    64 in binary: xxxxxxxx  */
/*                            */
/*  Bitshift right (>>=1)     */
/*    64 in binary: 01000000  */
/*    32 in binary: xxxxxxxx  */
/*                            */
/*  Bitshift left (<<=1)      */
/*     1 in binary: 00000001  */
/*     2 in binary: xxxxxxxx  */


void convert_to_binary(char number) {
  unsigned char bit, mask = 128;  /* 10000000 in binary */
  do {
    bit = (number & mask) / mask;
    printf("%d", bit);
  } while(mask >>= 1);
  printf("\n");
}

int main() {
  {
    printf("******** Signed ********:\n");
    char c = -128;           /* 10000000 in binary */
    printf("Bitshift right (>>=1)\n");
    printf("%4d in binary: ", c);
    convert_to_binary(c);

    c >>= 1;
    printf("%4d in binary: ", c);
    convert_to_binary(c);

    c = 64;                  /* 01000000 in binary */
    printf("\n");
    printf("Bitshift right (>>=1)\n");
    printf("%4d in binary: ", c);
    convert_to_binary(c);

    c >>= 1;
    printf("%4d in binary: ", c);
    convert_to_binary(c);


    c = 1;                   /* 00000001 in binary */
    printf("\n");
    printf("Bitshift left (<<=1)\n");
    printf("%4d in binary: ", c);
    convert_to_binary(c);

    c <<= 1;
    printf("%4d in binary: ", c);
    convert_to_binary(c);
  }

  printf("\n");

  /* unsigned */
  {
    printf("\n******* Unsigned *******:\n");
    unsigned char c = -128;  /* 10000000 in binary */
    printf("Bitshift right (>>=1)\n");
    printf("%4d in binary: ", c);
    convert_to_binary(c);

    c >>= 1;
    printf("%4d in binary: ", c);
    convert_to_binary(c);

    c = 64;                  /* 01000000 in binary */
    printf("\n");
    printf("Bitshift right (>>=1)\n");
    printf("%4d in binary: ", c);
    convert_to_binary(c);

    c >>= 1;
    printf("%4d in binary: ", c);
    convert_to_binary(c);


    printf("\n");
    printf("Bitshift left (<<=1)\n");
    c = 1;                   /* 00000001 in binary */
    printf("%4d in binary: ", c);
    convert_to_binary(c);

    c <<= 1;
    printf("%4d in binary: ", c);
    convert_to_binary(c);
  }
  return 0;
}