Problem about function stoi() for convert a string

[janluca91]

Hi, I have a problem with the following lines of code

 	friend ifstream& operator>>( ifstream& input, Publicazioni& obj)
		{
		std::string::size_type sz; 
		string buffer;
		getline(input,buffer);
		if(obj.titolo!=0) delete(obj.titolo);
		obj.titolo=new char[buffer.length()+1];
		strcpy(obj.titolo,buffer.c_str());
		getline(input,buffer);
		if(obj.autore!=0) delete(obj.autore);
		obj.autore=new char[buffer.length()+1];
		strcpy(obj.autore,buffer.c_str());
		getline(input,buffer);
		if(obj.casa_editrice!=0) delete(obj.casa_editrice);
		obj.casa_editrice=new char[buffer.length()+1];
		strcpy(obj.casa_editrice,buffer.c_str());
		getline(input,buffer);
		obj.numero=stoi(buffer,&sz);
		getline(input,buffer);
		obj.anno=stoi(buffer,&sz);
		getline(input,buffer);
		obj.pagine=stoi(buffer,&sz);
		return input;
		}

The compiler give me this error:"stoi was not declared in this scope.
In the Head of the program I have called the following libraries:

#include<iostream>
#include<cstring>
#include<string>
#include<stdlib.h>
#include<fstream> 

although stoi is a function of <string>,why does the compiler give me a mistake?
Thank you in advance.

[nvrmnd]

it's a C++11 function, try compiling w/ -std=c++11 or possibly -std=c++0x