C · Chapter 5 of 45
C Output (printf)
The printf() function is used to print output to the screen. It is part of the standard input/output library, so you must include <stdio.h> to use it.
printf uses format specifiers like %d for integers, %f for floats, %c for characters, and %s for strings to insert variable values into the output text.
Syntax
printf("format string", values...);Format specifiers
Common specifiers include %d (int), %f (float/double), %c (char), %s (string), and %p (pointer). The specifier must match the type of the value being printed.
Escape sequences
Special characters like newline (\n) and tab (\t) let you control formatting inside strings. \\ prints a literal backslash and \" prints a literal quote.
Example 1 (c)
#include <stdio.h>
int main() {
int age = 30;
printf("Age: %d\n", age);
return 0;
}Output
Age: 30%d is replaced by the integer value of age.
Example 2 (c)
#include <stdio.h>
int main() {
printf("Name: %s, Score: %.1f\n", "Amy", 9.5);
return 0;
}Output
Name: Amy, Score: 9.5%s prints a string and %.1f prints a float with one decimal place.
Key points
- printf() requires #include <stdio.h>.
- Format specifiers must match the argument type.
- \n creates a new line in the output.
- Multiple values can be printed in one printf call.
💡 Note: Mismatching a format specifier and argument type is undefined behavior and a common source of bugs.