Must iostream always be included?

Question

Must #include <iostream> be in the header of every C++code? Could you get by using other libraries instead?

Answer 1

What headers you need to include depends on what your program does. Does your program require input and output streams? If so, you need <iostream>. If you're asking about a different way to do console I/O, you can check <cstdio> (or <stdio.h>), which contains functions like printf() and scanf().

#include <cstdio>

int main() {
printf("Hello, World.");
}

If your program does not require any input and output functionalities, a program without including any headers, as such:

int main() { }

is completely valid.