Chapter 2, float data type, 4 

unix> cat float4.c
#include <stdio.h>
#include <math.h>
void printfloat2(int);

main()
{
    int i, low, high;
    printf("enter lower power of 2 ");
    scanf("%d%", &low);
    printf("enter higher power of 2 ");
    scanf("%d", &high);

    printf("\n         2**exp        Hex  +-  exp+127 1.     fraction\n\n");
    for (i = low; i <= high; i++) {
        printfloat2(i);
    }
    printf("\n");
}
void printfloat2(int exp)
{
    unsigned long i;
    union floatandlong {
        float asfloat;
        long  aslong;
    } bits32;
    bits32.asfloat = ldexp(1.0, exp);  /* 1.0 * 2**exp */ 
    printf(" %14d   %8.8x   ", exp, 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 float4.c
unix> ./a.out
enter lower power of 2 -10
enter higher power of 2 10

         2**exp        Hex  +-  exp+127 1.     fraction

            -10   3a800000   0 01110101   00000000000000000000000
             -9   3b000000   0 01110110   00000000000000000000000
             -8   3b800000   0 01110111   00000000000000000000000
             -7   3c000000   0 01111000   00000000000000000000000
             -6   3c800000   0 01111001   00000000000000000000000
             -5   3d000000   0 01111010   00000000000000000000000
             -4   3d800000   0 01111011   00000000000000000000000
             -3   3e000000   0 01111100   00000000000000000000000
             -2   3e800000   0 01111101   00000000000000000000000
             -1   3f000000   0 01111110   00000000000000000000000
              0   3f800000   0 01111111   00000000000000000000000
              1   40000000   0 10000000   00000000000000000000000
              2   40800000   0 10000001   00000000000000000000000
              3   41000000   0 10000010   00000000000000000000000
              4   41800000   0 10000011   00000000000000000000000
              5   42000000   0 10000100   00000000000000000000000
              6   42800000   0 10000101   00000000000000000000000
              7   43000000   0 10000110   00000000000000000000000
              8   43800000   0 10000111   00000000000000000000000
              9   44000000   0 10001000   00000000000000000000000
             10   44800000   0 10001001   00000000000000000000000

CIS-Linux2:~/oct14>./a.out
enter lower power of 2 -140
enter higher power of 2 -120

         2**exp        Hex  +-  exp+127 1.     fraction

           -140   00000200   0 00000000   00000000000001000000000
           -139   00000400   0 00000000   00000000000010000000000
           -138   00000800   0 00000000   00000000000100000000000
           -137   00001000   0 00000000   00000000001000000000000
           -136   00002000   0 00000000   00000000010000000000000
           -135   00004000   0 00000000   00000000100000000000000
           -134   00008000   0 00000000   00000001000000000000000
           -133   00010000   0 00000000   00000010000000000000000
           -132   00020000   0 00000000   00000100000000000000000
           -131   00040000   0 00000000   00001000000000000000000
           -130   00080000   0 00000000   00010000000000000000000
           -129   00100000   0 00000000   00100000000000000000000
           -128   00200000   0 00000000   01000000000000000000000
           -127   00400000   0 00000000   10000000000000000000000
           -126   00800000   0 00000001   00000000000000000000000
           -125   01000000   0 00000010   00000000000000000000000
           -124   01800000   0 00000011   00000000000000000000000
           -123   02000000   0 00000100   00000000000000000000000
           -122   02800000   0 00000101   00000000000000000000000
           -121   03000000   0 00000110   00000000000000000000000
           -120   03800000   0 00000111   00000000000000000000000
CIS-Linux2:~/oct14>