Output in C — printf() and Format Specifiers

Every program needs to communicate its results to the user. In C, the primary function for displaying output on the screen is printf(). It is defined in the stdio.h header file, which is why you almost always write #include <stdio.h> at the top of every C program.

The printf() Function

The name printf stands for print formatted. It lets you print text, numbers, and the values of variables to the screen in a precise, controlled format.