Unit-I Chapter 2 C Tokens: Character set, Identifiers, …

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C Programming – Types of Constants (Part 6)

Suitable for BCA, B.Tech, Diploma, or beginner programmers.

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What are Constants in C?

A constant is a fixed value that does not change during the execution of a program.

Constants are used in programs to make them more readable and maintainable.

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Types of Constants in C

C supports several types of constants, broadly categorized as:

1⃣ Integer Constants

• Whole numbers without decimal.
• Example: 10, -5, 0, 2000

Types:

• Decimal (Base 10): 25
• Octal (Base 8): starts with 0, e.g. 037
• Hexadecimal (Base 16): starts with 0x, e.g. 0x1F

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2⃣ Floating-point Constants

• Numbers with decimal point or in exponential (scientific) notation.
• Example: 3.14, -0.001, 2.5e3

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3⃣ Character Constants

• A single character enclosed in single quotes ' '.
• Example: 'A', 'z', '5'

Each character constant has an ASCII value internally.

char ch = 'A'; // ASCII value = 65

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4⃣ String Constants

• A sequence of characters enclosed in double quotes " ".
• Example: "Hello", "1234", "C Programming"

char str[] = "Hello";

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5⃣ Enumeration Constants (enum)

• Used to define named integer constants.
• Improves readability of code.

enum Days { MON, TUE, WED, THU, FRI };

Here, MON is 0, TUE is 1, etc.

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6⃣ Defined Constants (#define)

• Use the preprocessor directive #define to create constants.

#define PI 3.14
#define MAX 100

Once defined, PI will always be replaced with 3.14.

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Summary Table

Constant Type	Example
Integer	100, -23
Floating-point	3.14, 2.0e3
Character	'A', '7'
String	"Hello"
Enumeration	enum Colors {RED, BLUE}
Defined (#define)	#define PI 3.14

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Tips

• Constants make code easier to read and maintain.
• Use const keyword to declare variables as constants:

const int age = 18; // age cannot be changed

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Would you like:

• Practice questions on constants?
• A PDF revision sheet?
• A quiz to test your understanding?

Let me know, and I’ll provide it!

Type of C Contants- part 6

Programming in C with Numerical Methods Unit I Chapter II …