⌨️ Input and Output in C Programming

Learn printf() and scanf() With Examples

How Programs Communicate With Users 🚀

🚀 Introduction

A computer program is not useful if it only performs fixed tasks. Programs need to communicate with users.

This communication happens through:

📥 Input

Data provided by the user to the program.

📤 Output

Information displayed by the program.

🖥️ printf() Function in C

The printf() function is used to display output on the screen.

printf("Hello World");

Output:

Hello World

🔤 Format Specifiers in C

Specifier	Data Type	Example
%d	Integer	25
%f	Float	10.5
%c	Character	A
%s	String	Hello

⌨️ scanf() Function in C

The scanf() function is used to take input from the user.

scanf("%d",&number);

The & symbol gives the memory address of the variable.

💻 Example: Add Two Numbers

#include <stdio.h>

int main()
{

int a,b,sum;


printf("Enter first number: ");

scanf("%d",&a);


printf("Enter second number: ");

scanf("%d",&b);


sum = a + b;


printf("Sum = %d",sum);


return 0;

}

🔄 Program Execution Flow

User Input
⬇️
scanf()
⬇️
Processing
⬇️
printf()
⬇️
Output Display

🖥️ Output Example

Enter first number: 10
Enter second number: 20
Sum = 30

⚠️ Common Mistakes Beginners Make

• Forgetting & symbol in scanf()
• Using wrong format specifier
• Missing semicolon (;)
• Incorrect variable type

🚀 Practice Programs

• Take user's name and display it
• Calculate area of rectangle
• Convert Celsius to Fahrenheit
• Create a simple calculator
• Calculate student marks percentage

🎯 Conclusion

Input and Output are essential parts of every programming language. With printf() and scanf(), your programs can interact with users.

Next: Decision Making in C (if-else Statement) 🚀