蓝桥杯 - 基础练习十六进制转十进制（C语言版）_c语言十六进制转10进制用switch

题目：

代码如下：

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
 
/*
 * 十六进制转十进制
 * 作者：踏歌行
 * 日期：2018 - 3 - 17
**/
 
int main()
{
    int i;
    int len = 0;        //计算SUM长度
    char SUM[50];       //存储结果
    double index = 0;   //16的多少次幂
    long long sum = 0;  //结果
    int s_n = 0;        //计算十六进制数组长度
    double sixteen_1[8];//将输入的字符串数组转换成实数存入其中
    char sixteen[8];    //输入的字符串数组
    scanf("%s",sixteen);
    for(i = 0; i < 8; i++)
    {
        switch(sixteen[i])
        {
        case '0':
            sixteen_1[s_n++] = 0;
            break;
        case '1':
            sixteen_1[s_n++] = 1;
            break;
        case '2':
            sixteen_1[s_n++] = 2;
            break;
        case '3':
            sixteen_1[s_n++] = 3;
            break;
        case '4':
            sixteen_1[s_n++] = 4;
            break;
        case '5':
            sixteen_1[s_n++] = 5;
            break;
        case '6':
            sixteen_1[s_n++] = 6;
            break;
        case '7':
            sixteen_1[s_n++] = 7;
            break;
        case '8':
            sixteen_1[s_n++] = 8;
            break;
        case '9':
            sixteen_1[s_n++] = 9;
            break;
        case 'A':
            sixteen_1[s_n++] = 10;
            break;
        case 'B':
            sixteen_1[s_n++] = 11;
            break;
        case 'C':
            sixteen_1[s_n++] = 12;
            break;
        case 'D':
            sixteen_1[s_n++] = 13;
            break;
        case 'E':
            sixteen_1[s_n++] = 14;
            break;
        case 'F':
            sixteen_1[s_n++] = 15;
            break;
        }
    }
    index = (double)s_n;
    for(i = 0; i < s_n; i++)
    {
        sum += sixteen_1[i] * pow(16,index - 1);
        index--;
    }
    if(sum == 0)
    {
        SUM[len++] = '0';
    }
    else
    {
        for(; sum > 0; )
        {
            SUM[len++] = sum % 10 + '0';
            sum /= 10;
        }
    }
    for(i = len - 1; i >= 0; i--)
    {
        printf("%c",SUM[i]);
    }
    return 0;
}

运行结果如下：