“编写一个程序来确定char,short,int和long变量的范围,包括有符号和无符号,通过从标准头文件中打印适当的值并直接计算.如果你计算它们会更难：确定各种浮动的范围 – 点类型.“

我已经设法确定除浮点之外的所有类型的范围,通过使用标准头中的最小值和最大值以及直接计算.

如何使用直接计算确定浮点类型的范围？

#include <stdio.h>
#include <limits.h>
#include <float.h>

#define TESTBIT 2

/* write a program to determine the ranges of char,int,and long variables,both signed and unsigned by printing appropriate values from standard headers
   and by direct computation

   harder if you compute them - determine the ranges of the varIoUs floating-point types */
main()
{
    char ch,chtest;
    unsigned char uch;
    short sh,shtest;
    unsigned short ush;
    int i,itest;
    unsigned int ui;
    long l,ltest;
    unsigned long ul;
    long long ll,lltest;
    unsigned long long ull;

    ch = uch = sh = ush = i = ui = l = ul = ll = ull = 0;
    ++ch;        /* Maximum and minimum ranges using direct computation */
    chtest = 0;
    while (chtest >= 0) {
        chtest = ch * TESTBIT;
        if (chtest > 0)
            ch = ch * TESTBIT;
    }
    ch = ch * 2;
    printf("Minimum range of signed char variable: %d\n",ch);

    --ch;
    printf("Maximum range of signed char variable: %d\n",ch);

    --uch;
    printf("Maximum range of unsigned char variable: %u\n",uch);

    ++sh;
    shtest = 0;
    while (shtest >= 0) {
        shtest = sh * TESTBIT;
        if (shtest > 0)
            sh = sh * TESTBIT;
    }
    sh = sh * 2;
    printf("Minimum range of signed short variable: %d\n",sh);

    --sh;
    printf("Maximum range of signed short variable: %d\n",sh);

    --ush;
    printf("Maximum range of unsigned short variable: %u\n",ush);

    ++i;
    itest = 0;
    while (itest >= 0) {
        itest = i * TESTBIT;
        if (itest > 0)
            i = i * TESTBIT;
    }
    i = i * 2;
    printf("Minimum range of signed int variable: %d\n",i);

    --i;
    printf("Maximum range of signed int variable: %d\n",i);

    --ui;
    printf("Maximum range of unsigned int variable: %u\n",ui);

    ++l;
    ltest = 0;
    while (ltest >= 0) {
        ltest = l * TESTBIT;
        if (ltest > 0)
            l = l * TESTBIT;
    }
    l = l * 2;
    printf("Minimum range of signed long variable: %d\n",l);

    --l;
    printf("Maximum range of signed long variable: %d\n",l);

    --ul;
    printf("Maximum range of unsigned long variable: %lu\n",ul);

    ++ll;
    lltest = 0;
    while (lltest >= 0) {
        lltest = ll * TESTBIT;
        if (lltest > 0)
            ll = ll * TESTBIT;
    }
    ll = ll * 2;
    printf("Minimum range of signed long long variable: %lld\n",ll);

    --ll;
    printf("Maximum range of signed long long variable: %lld\n",ll);

    --ull;
    printf("Maximum range of unsigned long long variable: %llu\n",ull);

    printf("\nSize of char: %d\n",CHAR_BIT);    /* Max and min ranges using limits.h and float.h header */
    printf("Minimum range of signed char variable: %d\n",SCHAR_MIN);
    printf("Maximum range of signed char variable: %d\n",SCHAR_MAX);
    printf("Maximum range of unsigned char variable: %u\n",UCHAR_MAX);
    printf("Minimum range of signed short variable: %d\n",SHRT_MIN);
    printf("Maximum range of signed short variable: %d\n",SHRT_MAX);
    printf("Maximum range of unsigned short variable: %u\n",USHRT_MAX);
    printf("Minimum range of int variable: %d\n",INT_MIN);
    printf("Maximum range of int variable: %d\n",INT_MAX);
    printf("Maximum range of unsigned int variable: %u\n",UINT_MAX);
    printf("Minimum range of signed long variable: %ld\n",LONG_MIN);
    printf("Maximum range of signed long variable: %ld\n",LONG_MAX);
    printf("Maximum range of unsigned long variable: %lu\n",ULONG_MAX);
    printf("Minimum range of long long variable: %lld\n",LLONG_MIN);
    printf("Maximum range of long long variable: %lld\n",LLONG_MAX);
    printf("Maximum range of unsigned long long variable: %llu\n\n",ULONG_LONG_MAX);
    printf("Minimum range of float variable: %f\n",FLT_MIN);
    printf("Maximum range of float variable: %f\n",FLT_MAX);
    printf("Minimum range of double variable: %f\n",DBL_MIN);
    printf("Maximum range of double variable: %f\n",DBL_MAX);
    printf("Minimum range of long double variable: %lf\n",LDBL_MIN);
    printf("Maximum range of long double variable: %lf\n",LDBL_MAX);
    return 0;
}