How to trim a string in C++

cpp_trim

#include <iostream>
#include <string>

using namespace std;

string trim(string& str)
{
    size_t first = str.find_first_not_of(' ');
    size_t last = str.find_last_not_of(' ');
    return str.substr(first, (last-first+1));
}

int main() {
    string s = "abc ";
    cout << trim(s);
}