How to write Hello World in C

Write the program

Save this source as hello.c. The .c extension identifies C source code.

#include <stdio.h>

int main(void)
{
    printf("Hello, World!\n");
    return 0;
}

Include the declaration

stdio.h declares printf. Include the correct standard header before calling a library function.

Start in main

A hosted C program begins at main. Writing main(void) explicitly says that it accepts no arguments.

Finish successfully

\n starts a new output line. Returning zero reports success to the operating system; reaching the end of main also returns zero in modern C.