Lecture 2 Notes

Subject: Variables, Data Types, and Operators

Introduction

• Today we will discuss variables, data types, and operators.
• See the channel's playlist for other DSA concepts.
• Share lecture updates and progress on Twitter.

C++ Programming

• Writing the first program in C++.
• Producing output using cout.
  • Example: cout << "Hello World!";
• C++ is a case-sensitive language.
• The process of creating a folder to write code when using VS Code.

C++ Program Structure

1. Main Function: int main()
   • Program starting point.
   • Main logic code is written here.
2. Preliminary Directive: #include <iostream>
   • Necessary for input and output.
3. For clarity: using namespace std;
   • Using the standard namespace.

Output Statements

• Printing output using cout.
• Use a semicolon to end every statement.
• Use endl to move to a new line.

Variables and Data Types

• Variable: A container to store data.
• Different data types:
  • int (integer)
  • char (single character)
  • float (decimal number)
  • bool (true or false)
  • double (decimal number, for more precision)
• Variable names must always start with a letter or an underscore.

Type Casting

• Type Casting: Changing from a smaller data type to a larger data type.
  • Example: int new_price = (int) price;
• Type Conversion: Automatic change, such as float to double.

Taking Input

• Taking data from the user using cin.
  • Example: cin >> age;
• Output: cout << "Your age is: " << age;

Operators

1. Arithmetic Operators: +, -, *, /, % (modulo)
2. Relational Operators: <, >, ==, !=, <=, >=
3. Logical Operators: && (and), || (or), ! (not)
4. Unary Operators: ++ (increment), -- (decrement)

Conclusion of Programming

• A homework problem to create a simple calculator program.
• A mix of input, operation, and output.

Conclusion

• Covered principles of variables, data types, input, output, and operators in C++.
• Understanding of the basic structure and logic of programming.

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Homework

• Create a calculator program that can perform all four operations (addition, subtraction, multiplication, division).
• Confirm the success of Lecture 2 by sharing the date and what was learned in the comments.