How to declare user defined function with variant no of arguments in c? like printf.

[sajad ahmed]

for example the printf function can take different no of arguments:
printf("%d%d",x,y); //here it takes only 3 arguments
printf("%d%d%d",a,b,c); // n here it takes 4 argumets

how can we declare user defined function like that, that can take many arguments,

i know when we use argv, argc as arguments in the main function. but i want a non main function behave like that.

[Banfa]

Yep you can declare a varidac function just like printf and scanf.

You use the ellipsis to the the compiler that a variable number of arguments with variable type follows, this is how printf is declared with an ellipsis int printf ( const char * format, ... );.

In the code of the function you use the macros in stdarg.h (or cstdarg for C++) to access the variables passed.

[johny10151981]

#include <stdio.h>
#include <stdarg.h>
void sum(char *msg, ...)
{
int total = 0;
va_list p;
int arg;
va_start(p, msg);
while ((arg = va_arg(p,int)) != 0) {
total += arg;
}
printf(msg, total);
va_end(p);
}
 

follow the above simple example

It will add up all integer numbers.

But if you send String instead of integer you wont get any error/warning message.

If you want to manage various type variable you will have to think something like printf function