C++ Can't subtract two strings

问题

I want to subtract two strings in this code, but it won't let me do it and gives an operator - error. This code basically tries to separate a full input name into two outputs: first and last names. Please Help! Thank you!

#include <iostream>
#include <cstdlib>
#include <string>
using namespace std;

string employeeName, firstName, lastName;
int pos1, difference;

int main() {
    cout << "Enter your full name: " << endl;
    getline(cin, employeeName);

    pos1 = employeeName.find(" ");
    difference = pos1 - 0;
    lastName = employeeName.erase(0,difference);
    firstName = employeeName - lastName;

    cout << lastName << firstName << endl;

    system("pause");
    return 0;
}

回答1:

You should use std::string::substr. Subtracting strings like that is invalid.

firstName = employeeName.substr(0, employeeName.find(" "));

The first parameter is the starting index of the substring you want to extract and the second parameter is the length of the substring.

回答2:

How would you define a minus operator for a string? Would you subtract from the beginning? Or the end?

Moreover, what is "cat" - "dog"? This operator wouldn't make sense.

Instead, you might want to use string indices, i.e. employeeName[i], and copy characters individually, or use std::string::substr or std::string::erase, as others have suggested.

I would find substr() the easiest, due to its ability to remove sections of string (in this case, the first and last name).