Trim line in C++

trimSample.cpp

#include <iostream>
using namespace std;

string trimLeft(const string& str)
{
    const auto strBegin = str.find_first_not_of(" \t");
    return str.substr(strBegin, str.length() - strBegin);
}


string trimRight(const string& str)
{
    const auto strEnd = str.find_last_not_of(" \t\r");
    return str.substr(0, strEnd + 1);
}

string trim(const string& str) {
    return trimLeft(trimRight(str));
}

int main() {
    const string str = "  ala   ";
    cout << "--" << str << "--" << endl;
    cout << "--" << trimLeft(str) << "--" << endl;
    cout << "--" << trimRight(str) << "--" << endl;
    cout << "--" << trim(str) << "--" << endl;
}