How to declare printf()?

Question

I wanted to print something using printf() function in C, without including stdio.h, so I wrote program as :

int printf(char *, ...);
int main(void)
{
        printf("hello world\n");
        return 0;
}

Is the above program correct ?

Answer 1

The correct declaration (ISO/IEC 9899:1999) is:

int printf(const char * restrict format, ... );

But it would be easiest and safest to just #include <stdio.h>.

Answer 2

Just:

man 3 printf

It will tell you printf signature:

int printf(const char *format, ...);

this is the right one.