Chapter 2, float data type, 2 

unix> cat float2.c
#include <stdio.h>
#define DELTA 8
void printfloat(float);

main()
{
    float x;
    printf("\n          Dec        Hex  +-  exp+127 1.     fraction\n\n");
    for (x = -DELTA; x <= DELTA; x++)
        printfloat(x);
    printf("\n");
}

void printfloat(float x)
{
    unsigned long i;
    union floatandlong {
        float asfloat;
        long  aslong;
    } bits32;

    bits32.asfloat = x;
    printf(" %12.2f   %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 float2.c
unix> ./a.out

          Dec        Hex  +-  exp+127 1.     fraction

        -8.00   c1000000   1 10000010   00000000000000000000000
        -7.00   c0e00000   1 10000001   11000000000000000000000
        -6.00   c0c00000   1 10000001   10000000000000000000000
        -5.00   c0a00000   1 10000001   01000000000000000000000
        -4.00   c0800000   1 10000001   00000000000000000000000
        -3.00   c0400000   1 10000000   10000000000000000000000
        -2.00   c0000000   1 10000000   00000000000000000000000
        -1.00   bf800000   1 01111111   00000000000000000000000
         0.00   00000000   0 00000000   00000000000000000000000
         1.00   3f800000   0 01111111   00000000000000000000000
         2.00   40000000   0 10000000   00000000000000000000000
         3.00   40400000   0 10000000   10000000000000000000000
         4.00   40800000   0 10000001   00000000000000000000000
         5.00   40a00000   0 10000001   01000000000000000000000
         6.00   40c00000   0 10000001   10000000000000000000000
         7.00   40e00000   0 10000001   11000000000000000000000
         8.00   41000000   0 10000010   00000000000000000000000
unix>