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.

1️⃣ What is a Character Data Type?

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

📌 Characters are stored internally as ASCII values

2️⃣ Size of char

✔ Always 1 byte (8 bits)

3️⃣ ASCII Value Concept ⭐

Each character has a numeric ASCII code.

4️⃣ 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

5️⃣ Example: Signed vs Unsigned char

✔ Very important in embedded & system programming

6️⃣ Character Input & Output ⭐

Input

Output

7️⃣ Character Arithmetic 🔢

✔ Because characters are stored as numbers

8️⃣ char vs int (Important Difference)

✔ char saves memory

9️⃣ char in Strings ⭐

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

🔟 Special Characters in char

1️⃣1️⃣ char with <ctype.h> Functions 🔥

Common functions:

• isalpha()

• isdigit()

• islower()

• toupper()

• tolower()

1️⃣2️⃣ 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