C++11 formatting example using variadic template args

format.cpp

/*
	Program output:

	mbn@cuba:~/Development$ clang -std=c++11  -o format format.cpp -lstdc++
	mbn@cuba:~/Development$ ./format 
	This is a foobar string with a 666 number
	This is a moobar string with a 333 number
	This is a foobar string with moobar and woobar with a 333 number
*/

#include <string>
#include <iostream>

class FString
{
public:
	FString() { }
	FString(const char *s) : buffer(s) { }

	void Format(const char *format)
	{
		buffer += format;
	}

	template<typename T, typename... Args>
	void Format(const char *format, T value, Args && ... args)
	{
		Format(FormatNextArg(format, value), args...);
	}
	
	template<typename... Args>
	void Format(const char *format, const std::string &str, Args && ... args)
	{
		Format(format, str.c_str(), args...);
	}

	template<typename... Args>
	void Format(const char *format, const FString &str, Args && ... args)
	{
		Format(format, str.GetBytes(), args...);
	}
	
	const char *GetBytes() const { return buffer.c_str(); }
	
private:
	const char *FormatNextArg(const char *format, ...)
	{
		va_list args;
		va_start(args, format);
		for (; format[0] != 0; format++)
		{
			if (format[0] == '%')
			{
				if (format[1] == 's')
				{
					buffer += va_arg(args, const char*);
					format += 2;
					break;
				}
				else if (format[1] == 'd')
				{
					buffer += std::to_string(va_arg(args, int));
					format += 2;
					break;
				}
			}
			buffer.push_back(format[0]);
		}
		va_end(args);
		return format;
	}
	
	std::string buffer;
};

int main(int, char**)
{
	FString s1, s2, s3;
	
	s1.Format("This is a %s string with a %d number", "foobar", 666);
	std::cout << s1.GetBytes() << std::endl;

	std::string moo = "moobar";
	s2.Format("This is a %s string with a %d number", moo, 333);
	std::cout << s2.GetBytes() << std::endl;
	
	FString woo = "woobar";
	s3.Format("This is a %s string with %s and %s with a %d number", "foobar", moo, woo, 333);
	std::cout << s3.GetBytes() << std::endl;

	return 0;
}