Standard I/O: printf(), scanf(), and Escape Sequences0%

Primitive Data Types (int, float, double, char) & Size Modifiers

Standard I/O: printf(), scanf(), and Escape Sequences

Beginner10 min read•Updated: 2026-10-22

🖨️ Standard I/O: printf(), scanf(), and Escape Sequences

Introduction

Input and output operations are how your program communicates with the user. In C, standard input and output are provided by the <stdio.h> library via two central functions: printf() and scanf().

📤 Output with `printf()`

printf() sends formatted text to the standard output terminal (stdout).

1#include <stdio.h>
2 
3int main(void) {
4    int age = 20;
5    double score = 95.5;
6    
7    printf("Age: %d, Score: %.1f%%\n", age, score);
8    return 0;
9}

📥 Input with `scanf()`

scanf() reads formatted data from the keyboard (stdin).

Important Warning

Critical Rule: You must pass the address-of (&) operator before non-pointer variables so scanf knows where to write in memory!

1#include <stdio.h>
2 
3int main(void) {
4    int rollNumber;
5    printf("Enter your roll number: ");
6    scanf("%d", &rollNumber);
7    
8    printf("Registered Roll Number: %d\n", rollNumber);
9    return 0;
10}

⚡ Essential Escape Sequences

Escape sequences are special character combinations prefixed with a backslash (\):

Sequence	Name	Description
`\n`	Newline	Moves the cursor to the beginning of the next line.
`\t`	Horizontal Tab	Skips forward to the next tab stop (typically 4 or 8 spaces).
`\\`	Backslash	Prints an actual backslash character.
`\"`	Double Quote	Prints a double quotation mark inside a string literal.
`\b`	Backspace	Moves the cursor back one character space.
`\r`	Carriage Return	Moves the cursor to the start of the current line.

📝 Practice Quiz

1
Why must the '&' operator be used before variable names in scanf("%d", &x)?

- A) To tell C it is a constant - B) To pass the variable's memory address (Correct) - C) To format the text - D) To prevent memory leaks

1
Which escape sequence moves the terminal cursor to a new line?

- A) \t - B) \r - C) \n (Correct) - D) \a

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Structure of a C Program & The main() Function	Primitive Data Types (int, float, double, char) & Size Modifiers

Practice Quiz

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📥 Input with scanf()

scanf() reads formatted data from the keyboard (stdin).

Important Warning

Critical Rule: You must pass the address-of (&) operator before non-pointer variables so scanf knows where to write in memory!

1#include <stdio.h>
2 
3int main(void) {
4    int rollNumber;
5    printf("Enter your roll number: ");
6    scanf("%d", &rollNumber);
7    
8    printf("Registered Roll Number: %d\n", rollNumber);
9    return 0;
10}

⚡ Essential Escape Sequences

Escape sequences are special character combinations prefixed with a backslash (\):

Sequence	Name	Description
`\n`	Newline	Moves the cursor to the beginning of the next line.
`\t`	Horizontal Tab	Skips forward to the next tab stop (typically 4 or 8 spaces).
`\\`	Backslash	Prints an actual backslash character.
`\"`	Double Quote	Prints a double quotation mark inside a string literal.
`\b`	Backspace	Moves the cursor back one character space.
`\r`	Carriage Return	Moves the cursor to the start of the current line.

📝 Practice Quiz

Why must the '&' operator be used before variable names in scanf("%d", &x)?

- A) To tell C it is a constant - B) To pass the variable's memory address (Correct) - C) To format the text - D) To prevent memory leaks

Which escape sequence moves the terminal cursor to a new line?

- A) \t - B) \r - C) \n (Correct) - D) \a

Previous Lesson

Next Lesson

Structure of a C Program & The main() Function

Primitive Data Types (int, float, double, char) & Size Modifiers

🖨️ Standard I/O: printf(), scanf(), and Escape Sequences

Introduction

📤 Output with printf()

📥 Input with scanf()

⚡ Essential Escape Sequences

📝 Practice Quiz

Primitive Data Types (int, float, double, char) & Size Modifiers

Related Lessons

Practice Quiz

Loading Page Content...

🖨️ Standard I/O: printf(), scanf(), and Escape Sequences

Introduction

📤 Output with printf()

📥 Input with scanf()

⚡ Essential Escape Sequences

📝 Practice Quiz

Primitive Data Types (int, float, double, char) & Size Modifiers

Related Lessons

Practice Quiz

📤 Output with `printf()`

📥 Input with `scanf()`

📤 Output with `printf()`

📥 Input with `scanf()`