#include <iostream>

using namespace std;

// 十六进制字符串的最大长度
#define MAX_HEX_STR_LEN 100

bool hexToDec(char shex[], int & idec)
{
    size_t i = 0, len = 0;
    int mid = 0;

    len = strlen(shex);
    if (len > MAX_HEX_STR_LEN) {
        return false;
    }

    idec = 0;
    for (i = 0; i < len; i++) {
        mid = 0;
        if (shex[i] >= ‘0‘ && shex[i] <= ‘9‘) {
            mid = shex[i] - ‘0‘;
        } else if (shex[i] >= ‘a‘ && shex[i] <= ‘f‘) {
            mid = shex[i] - ‘a‘ + 10;
        } else if (shex[i] >= ‘A‘ && shex[i] <= ‘F‘) {
            mid = shex[i] - ‘A‘ + 10;
        } else {
            return false;
        }

        // 移位表示变为2的n次方倍
        mid <<= ((len - i - 1) << 2);
        idec += mid;
    }
    return true;
}


int main(int argc, char * argv[])
{
    int a = 0;
    char s[] = "fae3";
    hexToDec(s, a);
    cout << a << endl;

    return 0;
}