stof function is not declared in this scope c++

Question

When I compile my code,I got this error

'stof' was not declared in this scope.

and my code is

#include<iostream>
#include<string.h>
using namespace std;

int main()
{
string str,str2;
cin>>str>>str2;
float a,b;
a = stof(str);  //error
b = stof(str2); //error
cout<<a+b;
return 0;
}

how to resolve this ??

Answer 1

此外， std::stof只能使用 c++11 版本编译，编译应为：

g++ -std=c++11 code.cc

Answer 2

std::stof位于标准 C++ 头文件<string> 。

Answer 3

With dev c++ you need to go to Project > Project Options (Ctrl +h) > Compiler > Code generation > Language standard and select GNU C++ 11

(Not too sure about the menu since i have the language set to italian but it's pretty much that)