c++ string formatting

stringf.cpp

#include <assert.h>
#include <string>

template<typename... T> std::string stringf(T... args) {
	int length = snprintf(0, 0, args...);
	if(length < 0) assert(("invalid arguments to stringf", false));
	std::string str(length, 0);
	snprintf(str.data(), length + 1, args...);
	return str;
}

/* Example usage:
 * std::string str = stringf("foo %d", 42);
 */