c++编写12345678012345678912+12值

以下是使用C++编写的计算12345678012345678912+12的代码：

#include <iostream>
#include <string>

using namespace std;

string add(string num1, string num2) {
    string res = "";
    int carry = 0;
    int i = num1.length() - 1, j = num2.length() - 1;
    while (i >= 0 || j >= 0 || carry != 0) {
        int n1 = i >= 0 ? num1[i] - '0' : 0;
        int n2 = j >= 0 ? num2[j] - '0' : 0;
        int sum = n1 + n2 + carry;
        carry = sum / 10;
        sum %= 10;
        res = to_string(sum) + res;
        i--;
        j--;
    }
    return res;
}

int main() {
    string num1 = "12345678012345678912", num2 = "12";
    string res = add(num1, num2);
    cout << num1 << " + " << num2 << " = " << res << endl;
    return 0;
}

运行结果为：

12345678012345678912 + 12 = 12345678012345678924