C++ std::string equivalent to Python's lstrip

In Python you can do

" test".lstrip()

whereas in C++ the easiest way is to use the the Boost String Algorithms library:

#include <boost/algorithm/string/trim.hpp>

using namespace boost::algorithm;

string to_trim = " test";
string trimmed = trim_left_copy(to_trim);

_copy in trim_left_copy() means that the original string is not modified.

Full example:

#include <iostream>
#include <string>
#include <boost/algorithm/string/trim.hpp>

using namespace std;
using namespace boost::algorithm;

int main() {
    string to_trim = " test";
    string trimmed = trim_left_copy(to_trim);
    cout << trimmed << endl; // Prints 'test'
}

In case you want to trim a custom set of characters, use trim_left_copy_if() together with is_any_of():

#include <iostream>
#include <string>
#include <boost/algorithm/string/trim.hpp>

using namespace std;
using namespace boost::algorithm;

int main() {
    string to_trim = "bbcaXtest";
    string trimmed = trim_left_copy_if(to_trim, is_any_of("abc"));
    cout << trimmed << endl; // Prints 'Xtest'
}