Understanding Printf() and Scanf().

What is printf?

Meaning:

printf means “print formatted” — it shows messages or numbers on the screen.

Think of it like:

Telling the computer:
“Say this out loud on the screen.”

Example:

printf("Hello!");

The computer will show:

Hello!

You can also print numbers:

int age = 10;
printf("I am %d years old", age);

Here:

• %d is a placeholder for a number.
• age is the number to show.

Output:

I am 10 years old

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What is scanf?

Meaning:

scanf means “scan formatted” — it reads what the user types on the keyboard.

Think of it like:

Telling the computer:
“Listen to the user and save what they type.”

Example:

int age;
scanf("%d", &age);

• %d means: “I’m reading a number.”
• &age means: “Put that number inside the age box.”

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Simple Program Using Both

#include <stdio.h>

int main() {
    int age;
    
    printf("Enter your age: ");
    scanf("%d", &age);

    printf("You are %d years old!", age);

    return 0;
}

What Happens:

1. printf() shows: Enter your age:
2. User types: 15
3. scanf() reads it and puts it into age.
4. printf() then shows: You are 15 years old!