converting string to float in c++

Question

What is the best way to convert a string to float(in c++), given that the string may be invalid. Here are the type of input

20.1

0.07

x

0

Answer 1

C++11 actually has functions that do this now, in your case std::stof

Note that as far as handling your validation, it will throw an std::invalid_argument exception if the argument cannot be converted.

For completeness, here are more of such functions

std::stoi    // string to int
std::stol    // string to long
std::stoll   // string to long long
std::stof    // string to float
std::stod    // string to double
std::stold   // string to long double