Variable arguments in C

Variable arguments can be passed to a function in C. The best example for this is the inbuilt printf function. For printf the first argument is a character array and variable number of arguments after that. This is implemented using macros within the stdarg header. When parameters are passed to a function , its copied to a stack created for that function. va_list and va_arg and va_end are macros which help traverse thru this stack. This is partial implementation of your own printf function.

	#include<stdarg.h>
	#include<iostream>
	using namespace std;
	void my_printf(char* format, ...)
	{
	va_list argp;
	va_start(argp, format);
	while (*format != '\0') {
	if (*format == '%') {
	format++;
	if (*format == '%') {
	putchar('%');
	} else if (*format == 'c') {
	char char_to_print = va_arg(argp, int);
	putchar(char_to_print);
	} else {
	fputs("Not implemented", stdout);
	}
	} else {
	putchar(*format);
	}
	format++;
	}
	va_end(argp);
	}
	int main()
	{
	my_printf((char *) "char %c %c", '1', '2');
	my_printf((char *) "string %c %c %d", '3', '4', 5);
	}

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