How to write a printf-like function.

// What we need#include <cstdarg>#include <iostream>#include <sstream>#include <string>// Cleaner codeusing std::string;using std::stringstream;using std::cout;string MyPrintf( const char* str, ... ){	// Store the length of the passed in string	int str_size = strlen(str);	// We do not want to process an empty string	if(str_size == 0)		return "";	// This is the delimeter that is used to specify the format flags	// you can use what you want.	static char delim = '%';	// Stores final output, use a stringstream for 	// easy output of all basic data types	stringstream output;	// A place to store the list of arguments	va_list arguments;	// Initializing arguments to store all values after the initial string	va_start(arguments, str);		for(int x = 0; x < str_size; x++)	{		// We know that delim is used to denote a start of a format, but if you		// wanted to use your own character, you'd add it here.		if(str[x] == delim)		{			// If there is a next character, and it is not a delim, ("delimdelim" means add a single delim)			// If you use your own character, replave the % with it!			if(x + 1 < str_size && str[x + 1] != delim)			{				// If we get in a string				if(str[x + 1] == 's')				{					// We have a c-string, so get it and save it					char* temp = va_arg(arguments, char*);					output << temp;					// We know what comes after the delim, so do not process it					x++;				}								// If we get in an integer				else if(str[x + 1] == 'i')				{					// We have an integer, so get it and save it					int temp = va_arg(arguments, int);					output << temp;					// We know what comes after the delim, so do not process it					x++;				}				// ... Continue on for what else you need			}			else if(x + 1 < str_size)			{				// Save the delim that "delimdelim" was used for				output << delim;				// We know what comes after the delim, so do not process it				x++;			}		}		else		{			// Save the character to the output string			output << str[x];		}	}	// Cleans up the list	va_end(arguments);	// Return the actual string	return output.str();}int main(int argc, char* argv[]){	// Create the string	string temp = MyPrintf("Hello %s must be at least %i years old", "world", 100);	// Just show what it is	cout << temp << "\n";	// Standard return	return 0;}

#include <stdio.h>#include <stdarg.h>const int max=1024;void debug(const char *s,...){    va_list va; va_start(va,s);    char buffer[max];    sprintf(max,"error: "); vsprintf(max,s,va); sprintf(max,"\n");    va_end(va); do_whatever_with(buffer);}