题解 | #进制转换#

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

int main(){

    char hex[34] = {0};
    long long s;

    fgets(hex, sizeof(hex), stdin);
    int len = strlen(hex) - 1;
    hex[len] = '\0';

    for(int i = 2; i<len; i++){
        if(hex[i]>='0' && hex[i]<='9')
            hex[i] = hex[i] - '0';
        else if(hex[i]>='a' && hex[i]<='f')
            hex[i] = hex[i] - 'a' + 10;
        else if(hex[i]>='A' && hex[i]<='F')
            hex[i] = hex[i] - 'A' + 10;
        
        s += hex[i] * pow(16, len - i - 1);
    }
    printf("%d",s);
    return 0;
}