Using printf for output in C

Introduction

We use printf to show messages or results on the screen. It helps us communicate what the program is doing.

To display a greeting message to the user.

To show the result of a calculation.

To print instructions or menus in a program.

To debug by showing variable values during program execution.

To format output nicely, like showing numbers with decimals.

Syntax

C

printf("format string", values...);

The format string tells printf what to print and how.

Placeholders like %d or %s are used to insert values.

Examples

Prints a simple message with a new line.

C

printf("Hello, world!\n");

Prints a number inside the message using %d for an integer.

C

printf("I have %d apples.\n", 5);

Prints a word or sentence using %s for a string.

C

printf("My name is %s.\n", "Anna");

Prints a floating-point number with 2 decimal places using %.2f.

C

printf("Pi is approximately %.2f.\n", 3.14159);

Sample Program

This program prints a greeting, then shows the age using %d to insert the number, and finally prints a closing message.

C

#include <stdio.h>

int main() {
    int age = 25;
    printf("Hello!\n");
    printf("I am %d years old.\n", age);
    printf("Nice to meet you!\n");
    return 0;
}

Important Notes

Always include \n at the end of your message to move to the next line.

Make sure the placeholders match the type of the values you provide (e.g., %d for int, %s for string).

printf does not add a new line automatically.

Summary

printf is used to show messages on the screen.

Use placeholders like %d, %s, and %f to insert values.

Remember to add \n to start a new line after printing.