Chapter 2, float data type, 3 

unix> cat float3.c
#include <stdio.h>
void printfloat(float);

main()
{
    float x = 1;
    int i;
    printf("\n            Dec        Hex  +-  exp+127 1.     fraction\n\n");
    for (i = 1; i <= 32; i++) {
        printfloat(x);
        x = x * 2;
    }
    printf("\n");
}
void printfloat(float x)
{
    unsigned long i;
    union floatandlong {
        float asfloat;
        long  aslong;
    } bits32;
    bits32.asfloat = x;
    printf(" %14.2f   %8.8x   ", bits32.asfloat, bits32.aslong);
    for (i = 0x80000000ul; i > 0; i>>=1) {
        if (i == 0x40000000ul)
            printf(" "); 
        if (i == 0x00400000ul)
            printf("   "); 
        printf("%c", (i & bits32.aslong ? '1' : '0')); 
    } 
    printf("\n");
}
unix> gcc float3.c
unix> ./a.out

            Dec        Hex  +-  exp+127 1.     fraction

           1.00   3f800000   0 01111111   00000000000000000000000
           2.00   40000000   0 10000000   00000000000000000000000
           4.00   40800000   0 10000001   00000000000000000000000
           8.00   41000000   0 10000010   00000000000000000000000
          16.00   41800000   0 10000011   00000000000000000000000
          32.00   42000000   0 10000100   00000000000000000000000
          64.00   42800000   0 10000101   00000000000000000000000
         128.00   43000000   0 10000110   00000000000000000000000
         256.00   43800000   0 10000111   00000000000000000000000
         512.00   44000000   0 10001000   00000000000000000000000
        1024.00   44800000   0 10001001   00000000000000000000000
        2048.00   45000000   0 10001010   00000000000000000000000
        4096.00   45800000   0 10001011   00000000000000000000000
        8192.00   46000000   0 10001100   00000000000000000000000
       16384.00   46800000   0 10001101   00000000000000000000000
       32768.00   47000000   0 10001110   00000000000000000000000
       65536.00   47800000   0 10001111   00000000000000000000000
      131072.00   48000000   0 10010000   00000000000000000000000
      262144.00   48800000   0 10010001   00000000000000000000000
      524288.00   49000000   0 10010010   00000000000000000000000
     1048576.00   49800000   0 10010011   00000000000000000000000
     2097152.00   4a000000   0 10010100   00000000000000000000000
     4194304.00   4a800000   0 10010101   00000000000000000000000
     8388608.00   4b000000   0 10010110   00000000000000000000000
    16777216.00   4b800000   0 10010111   00000000000000000000000
    33554432.00   4c000000   0 10011000   00000000000000000000000
    67108864.00   4c800000   0 10011001   00000000000000000000000
   134217728.00   4d000000   0 10011010   00000000000000000000000
   268435456.00   4d800000   0 10011011   00000000000000000000000
   536870912.00   4e000000   0 10011100   00000000000000000000000
  1073741824.00   4e800000   0 10011101   00000000000000000000000
  2147483648.00   4f000000   0 10011110   00000000000000000000000

unix>