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输入案例：±c2#

输出结果-194

#include<stdio.h>
#include<string.h>
#include<math.h>
#include<stdlib.h>
char s1[1000];
char s2[1000];
int a = 0;
int call(int a)//将每位十六进制符号转化为十进制
{
    int outcome = 0;
    if (a >= '0' && a <= '9')
    {
        outcome = a - 48;
    }
    else if ((a >= 'A' && a <= 'F'))
    {
        outcome = a - 55;
    }
    else
        outcome = a - 87;
    return outcome;
int main()
{
    int keys = 0;
    int n = 0;//确定是否有负号
    printf("请输入一个字符串：\n");
    gets_s(s1);//读入一串字符
    for (int i = 0,j=0;i < strlen(s1); i++)
    {
        if ((s1[i] >= '0' && s1[i] <= '9') || (s1[i] >= 'A' && s1[i] <= 'F') || (s1[i] >= 'a' && s1[i] <= 'f'))
        {
            s2[j] = s1[i];
            j++;
            if (j == 1)
                n++;
        }
        else
            continue;
    }//过滤掉其他字符
    printf("原始数组s1=%s\n", s1);
    printf("过滤后的数组s2=%s\n", s2);
    for (int i = strlen(s2)-1,k=0; i>=0; i--,k++)//倒着来的
    {
        keys = keys + ((call(s2[i])) * pow(16, k));
    }
    if (n == 1)
        printf("该十六进制值为:\n-");
    printf("%d", keys);
    system("pause");
    return 0;
}