printf

"printf" is a function in the C-standard library that outputs text to standard output. Standard output is typically the terminal or debug console, depending on the system the program is running on. The f stands for formatted, allowing the function to output not just fixed strings, but also text with variable data in it.

Hello world

The simplest of all C-programs is known as "Hello world" program. It outputs "Hello world", using printf.

#include <stdio.h>

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

Using parameters

Parameters need to be specified in the format string. A parameter definition starts with a % character. A simple example with one numerical parameter looks as below:

  printf("Total sum is: %d\n", Sum);