Converting from a std::string to bool

Question

What is the best way to convert a std::string to bool? I am calling a function that returns either \"0\" or \"1\", and I need a clean solution for turning this into a boole

Answer 1

There is also std::stoi in c++11:

bool value = std::stoi(someString.c_str());

Answer 2

It'll probably be overkill for you, but I'd use boost::lexical_cast

boost::lexical_cast<bool>("1") // returns true
boost::lexical_cast<bool>("0") // returns false

Answer 3

bool to_bool(std::string const &string) { 
    return string[0] == '1';
}

Answer 4

Here's a way similar to Kyle's except it handles the leading zeroes and stuff:

bool to_bool(std::string const& s) {
     return atoi(s.c_str());
}

Answer 5

If you need "true" and "false" string support consider Boost...

BOOST_TEST(convert<bool>( "true", cnv(std::boolalpha)).value_or(false) ==  true);
BOOST_TEST(convert<bool>("false", cnv(std::boolalpha)).value_or( true) == false);

BOOST_TEST(convert<bool>("1", cnv(std::noboolalpha)).value_or(false) ==  true);
BOOST_TEST(convert<bool>("0", cnv(std::noboolalpha)).value_or( true) == false);

https://www.boost.org/doc/libs/1_71_0/libs/convert/doc/html/boost_convert/converters_detail/stream_converter.html

Answer 6

bool to_bool(std::string const& s) {
     return s != "0";
}