C Character Data Types

 C Character Data Types (Complete Guide: Beginner → Advanced)

In C language, the character data type is used to store single characters or small numeric values (ASCII codes).
It is 1 byte in size and is extremely important for strings, input/output, and low-level programming.

 What is a Character Data Type?

A character data type (char) stores one character at a time.

•  Characters are stored internally as ASCII values

 Size of char

•  Always 1 byte (8 bits)

ASCII Value Concept

Each character has a numeric ASCII code.

 Types of char in C

C provides three variations of character type:

char

• Can be signed or unsigned (compiler dependent)

signed char

Range: −128 to 127

unsigned char

Range: 0 to 255

 Example: Signed vs Unsigned char

•  Very important in embedded & system programming

 Character Input & Output

Input

Output

 Character Arithmetic

•  Because characters are stored as numbers

char vs int (Important Difference)

• char saves memory

char in Strings

•  String = array of char
•  Ends with '\0' (null character)

 Special Characters in char

char with <ctype.h> Functions

Common functions:

• isalpha()

• isdigit()

• islower()

• toupper()

• tolower()

Common Mistakes

•  Using double quotes "A" instead of 'A' 
•  Forgetting & in scanf()
•  Assuming char is always signed
•  Confusing '0' and 0

 Interview Questions (Must Prepare)

1. Size of char in C?

2. Difference between char and unsigned char?

3. What is ASCII?

4. Output of char c = 65; printf("%c", c);

5. Difference between 'A' and "A"?

 Real-Life Use Cases

• String processing

• Text files

• Keyboard input

• Embedded systems

• Byte-level operations

Summary

• char stores a single character
•  Always 1 byte
• Uses ASCII internally
• signed & unsigned affect range
•  Essential for strings, I/O & system programming