十进制实数转化为二进制、八进制、十六进制的实数

转化过程非常简单，就是整数部分对进制辗转取于，小数部分乘以进制，大于整数进位否则取0；

如12.56，小数部分转化为二进制：

0.56*2 = 1.12  取 1

0.12*2 = 0.24 取 0

0.24*2 = .48 取 0

0.48*2 = 0.96 取 0

0.96*2 = 1.92 取 1

……依次类推、、、

#include <stdio.h>
#include <string.h>

void two(int x, float y)
{
    int a[1000], b[1000];
    int t = 5;
    int i = 0, j = 0;
    while(x)
    {
        a[i++] = x%2;
        x /= 2;
    }
    while(t--)
    {
        float p = 2.0*y;
        if(p >= 1)
        {
            b[j++] = 1;
            y = p-1;
        }
        else
        {
            b[j++] = 0;
            y = p;
        }
    }
    for(int k = i-1; k >= 0; k--)
        printf("%d",a[k]);
    printf(".");
    for(int k = 0; k < j; k++)
        printf("%d",b[k]);
    printf("\n");
}

void eight(int x, float y)
{
    int a[120], b[120], i = 0, j = 0;
    int t = 5;
    while(x)
    {
        a[i++] = x%8;
        x /= 8;
    }
    while(t--)
    {
        float p = 8*y;
        float q = p;
        int xx = (int)p;
        if(xx >= 1)
        {
            b[j++] = xx;
            y = q-xx;
        }
        else
        {
            b[j++] = 0;
            y = q;
        }
    }
    for(int k = i-1; k >= 0; k--)
        printf("%d",a[k]);
    printf(".");
    for(int k = 0; k < j; k++)
        printf("%d",b[k]);
    printf("\n");
}

void sixteen(int x, float y)
{
    int i = 0, j = 0, t = 5;
    char a[120], b[120];
    while(x)
    {
        int p = x%16;
        if(p == 10)
        a[i++] = 'A';
        else if(p == 11)
        a[i++] = 'B';
        else if(p == 12)
        a[i++] = 'C';
        else if(p == 13)
        a[i++] = 'D';
        else if(p == 14)
        a[i++] = 'E';
        else if(p == 15)
        a[i++] = 'F';
        else
        a[i++] = p+'0';
        x /= 16;
    }
    while(t--)
    {
        float yy = 16*y;
        float pp = yy;
        int xx = (int)yy;
        if(xx >= 10)
        {
            b[j++] = 'A'+xx-10;
            y = pp-xx;
        }
        else if(xx >= 1)
        {
            b[j++] = xx+'0';
            y = pp-xx;
        }
        else
        {
            y = pp;
        }
    }
    for(int k = i-1; k >= 0; k--)
        printf("%c",a[k]);
    printf(".");
    for(int k = 0; k < j; k++)
        printf("%c",b[k]);
    printf("\n");
}

int main()//进制转换，每次只取小数点后五位
{
    float x, y, z;
    int t;
    while(~scanf("%f",&z))
    {
        x = z;
        t = (int)z;
        y = x-t;
        two(t,  y);//二进制转化
        eight(t,  y);//八进制转化
        sixteen(t,  y);//十六进制转换
    }
    return 0;
}