#include<iostream>
#include<string>
using namespace std;
int main()
{
string alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
int num[26] = {10,11,12,13,14,15,16,17,34,18,19,20,21,22,35,23,24,25,26,27,28,29,32,30,31,33};
string a;
int alpToNum = 0;
int sum = 0;
while (cin>>a)
{
for (int i = 0; i < 26; i++)
{
if (a[0] == alpha[i])
{
alpToNum = num[i];
break;
}
}
sum += (alpToNum % 10) * 9;
sum += (alpToNum / 10);
for (int i = 1; i < a.length() - 1; i++)
{
sum += ((9 - i)*((a[i] - 48)));
}
sum += (a[a.length() - 1] - 48);
if (sum % 10 == 0)
cout << "real" << endl;
else
cout << "fake" << endl;
}
return 0;
}

請各位大大幫忙解惑

在while裡面記得每一輪sum都要初始為零。

原本的code只要輸入一次錯誤的身分證字號，之後都會是錯的，因為sum一直累加上去，就無法被10整除。

while (cin>>a){

sum = 0;

...

...

...

}