Constants, Variables and Keywords- part 5.

Constants, Variables, and Keywords – Part 5

 1. Constants:

Constants are fixed values that do not change during the execution of a program. They can be of various types, like integer constants, floating-point constants, character constants, and string constants.

Examples:

• Integer Constant: 5, -10, 100
• Floating-point Constant: 3.14, -0.99, 2.5e3
• Character Constant: 'A', 'b', '$'
• String Constant: "Hello", "12345"

 2. Variables:

Variables are memory locations that hold data and whose value can change during program execution.

• They should have meaningful names.
• The value stored in a variable can be updated.

Declaration and Initialization:

 3. Keywords:

Keywords are reserved words that have special meanings in programming languages. They cannot be used as variable names.

Examples of Keywords:

• In Python: if, else, while, for, def, return, break
• In C/C++: int, float, char, if, else, while, return, void
• In Java: class, static, public, void, new, try, catch

 Differences Summary:

 Quick Exercise:

1. Identify constants, variables, and keywords in the following line:
   count = 10
while count > 0:
print("Hello")
count -= 1

2. Write any 3 keywords of C language.

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Constants, Variables and Keywords- part 5.

5. Variables and Constants

Introduction to C

Here is Part 5 of the “Getting Started with C Programming” series, focusing on:

Constants, Variables, and Keywords in C

1. What are Constants in C?

Constants are fixed values that do not change during the execution of a program.

Types of Constants:

Example:

const keyword makes a variable read-only (cannot be modified later).

2. What are Variables in C?

A variable is a named location in memory used to store data temporarily.

Syntax:

Example:

Rules for Naming Variables:

• Must begin with a letter (A–Z or a–z) or underscore (_).

• No spaces or special characters.

• Case-sensitive (Total ≠ total).

• Avoid using keywords as variable names.

3. What are Keywords in C?

Keywords are reserved words with special meaning. They cannot be used as variable names.

Examples of Keywords in C:

Example:

c

CopyEdit

int return = 5; // Error! "return" is a keyword


Quick Recap:

Practice Questions:

1. Which of the following is a valid variable name?
   a) 1value
   b) value1
   c) float
   d) value#

Correct Answer: b) value1

2. What will happen if you try to change the value of a const variable?

It will give a compile-time error.

Would you like a quiz, worksheet, or Part 6: Data Types in C next?

unit-2 – constant,variable & data types

Constants, Variables and Keywords- part 5.

Variables and Constants – Pearson Higher Education