Long to string, string to long conversion.

Whats the easiest way to do that?

Stringstreams:

Code:

#include <iostream>
#include <string>
#include <sstream>

using namespace std;

int main(int argc, char *argv[]) {
// long to string
	int n = 123456789;
	ostringstream oss;
	oss << n;
	string s(oss.str());
	cout << s << endl;

// string to long
	n = 0;
	istringstream iss(s);
	iss >> n;
	cout << n << endl;

	return 0;
}

If you only have to do it once and don't want to instantiate the stringstream you could use a standard C function like strtol():

Code:

#include <cstdlib>

string s("123");
int n = strtol(s.c_str(), NULL, 0);

But there is no simple inverse of that.

or you could use boost::lexical_cast, and accept the fact that it has already been done

Code:

int n = boost::lexical_cast<int>(std::string("1234")); // Works on regular C-style strings, too
std::string s = boost::lexical_cast<std::string>(1234);

Requires boost, which you should have anyway (boost.org).