C Language Formatted Input/Output The printf() Function


Example

Accessed through including <stdio.h>, the function printf() is the primary tool used for printing text to the console in C.

printf("Hello world!");
// Hello world!

Normal, unformatted character arrays can be printed by themselves by placing them directly in between the parentheses.

printf("%d is the answer to life, the universe, and everything.", 42);
// 42 is the answer to life, the universe, and everything.

int x = 3;
char y = 'Z';
char* z = "Example";
printf("Int: %d, Char: %c, String: %s", x, y, z);
// Int: 3, Char: Z, String: Example

Alternatively, integers, floating-point numbers, characters, and more can be printed using the escape character %, followed by a character or sequence of characters denoting the format, known as the format specifier.

All additional arguments to the function printf() are separated by commas, and these arguments should be in the same order as the format specifiers. Additional arguments are ignored, while incorrectly typed arguments or a lack of arguments will cause errors or undefined behavior. Each argument can be either a literal value or a variable.

After successful execution, the number of characters printed is returned with type int. Otherwise, a failure returns a negative value.