Lecture 4: Introduction to C++

1. Introduction to C++

Definition

C++ is an object-oriented, high-level, cross-platform programming language that allows for the development of efficient, high-performance applications.
It was developed by Bjarne Stroustrup as an extension of C, providing programmers with more control over system resources and memory.

2. Why Use C++?

• One of the most popular programming languages worldwide.
• Used in operating systems, GUIs, game engines, and embedded systems.
• Supports object-oriented programming (OOP), enabling code reuse and modular design.
• Portable and adaptable across multiple platforms.
• Closely related to C, C#, and Java, making it easy to learn.

3. Key Features of C++

Feature	Description
Object-Oriented	Supports abstraction, encapsulation, inheritance, polymorphism, and data hiding.
Compiler-Based	Converts code directly to machine language for faster execution.
Manual Memory Management	Uses pointers and dynamic memory allocation.
High-Level Language	Uses human-readable syntax similar to English.
Simplicity	Divides programs into logical modules for readability.
Pointers	Variables that store memory addresses for direct manipulation.
Rich Library	Offers extensive built-in functions and libraries.
Operator Overloading	Allows redefining operators for user-defined data types.
Case Sensitive	Distinguishes between uppercase and lowercase letters.
Platform Dependent	Compiled code runs only on the system where it was built.
Portable Source Code	Source (.cpp) files can be compiled on different platforms.
Exception Handling	Handles runtime errors gracefully.

4. Difference Between C and C++

Aspect	C	C++
Programming Type	Procedural	Object-Oriented
Classes/Objects	Not supported	Supported
Data Security	No encapsulation	Supports encapsulation
Inheritance & Polymorphism	Not supported	Supported
Abstraction	Not supported	Supported
File Extension	.c	.cpp

5. Phases of the C++ Compilation Process

#	Phase	Description
1	Preprocessing	Handles #include, #define, and macros before compilation.
2	Lexical Analysis	Breaks source code into tokens (keywords, identifiers, etc.).
3	Syntax Analysis	Checks grammatical correctness according to C++ rules.
4	Semantic Analysis	Ensures logical correctness (valid declarations, types, etc.).
5	Intermediate Code Generation	Produces machine-independent intermediate code.
6	Code Optimization	Improves performance and reduces memory usage.
7	Code Generation	Converts code into assembly or machine language.
8	Linking	Combines object files and libraries into a final executable (.exe).

6. The Compilation and Linking Process

Step	Description	Output
1. Preprocessing	Handles directives like #include and #define.	.i file
2. Lexical Analysis	Converts source into tokens.	—
3. Syntax Analysis	Checks grammar and structure.	—
4. Semantic Analysis	Validates data types and logic.	—
5. Intermediate Code Generation	Produces machine-independent representation.	.ir
6. Code Optimization	Enhances efficiency.	—
7. Code Generation	Converts to assembly code.	.s
8. Assembly	Translates assembly to object code.	.o
9. Linking	Combines object code and libraries.	.exe

Compilation Flow:

hello.cpp -> hello.i -> hello.ir -> hello.s -> hello.o -> hello.exe

7. Errors in C++

Type	Detected When	Description
Compile-Time Error	During compilation	Syntax or grammar issues (e.g., missing semicolon).
Runtime Error	During execution	Errors such as division by zero.
Logical Error	After execution	Produces incorrect output due to logic mistakes.

Examples:

// Compile-time error
int x = 10
cout << x;

// Runtime error
int x = 15, y = 0;
cout << x / y;

// Logical error
int x = 10, y = 5;
cout << x * y; // Intended division

8. Development Environments

Text Editors

Used to write source code (e.g., Notepad).

IDEs (Integrated Development Environments)

Provide an all-in-one environment for writing, compiling, and debugging.
Examples:

• Dev C++
• Code::Blocks
• Eclipse
• Visual Studio

Advantages:

• Integrated compiler
• Debugging tools
• Auto-completion

9. Writing Your First C++ Program

#include <iostream>
using namespace std;

int main() {
  cout << "Hello World!";
  return 0;
}

Explanation

• #include <iostream> — Includes input/output functions.
• using namespace std; — Allows direct use of standard library functions.
• int main() — Entry point of every C++ program.
• cout — Displays output to the console.
• return 0; — Ends the program successfully.

Alternative:

#include <iostream>

int main() {
  std::cout << "Hello World!";
  return 0;
}

10. C++ Statements

• Each statement ends with a semicolon (;).
• Multiple statements execute sequentially.

Example:

cout << "Hello World!";
cout << "Welcome to C++!";

Output:

Hello World!Welcome to C++!

11. Output with cout

• Text must be in double quotes ("").
• Multiple outputs can be combined on a single line using <<.
• The << operator is known as the insertion operator.

Example:

cout << "The result is: " << 3;

12. Summary

• C++ is a high-level, object-oriented, compiler-based language.
• Developed by Bjarne Stroustrup as an extension of C.
• Offers manual memory management, operator overloading, and exception handling.
• The compilation process includes preprocessing, analysis, code generation, and linking.
• Errors are categorized as compile-time, runtime, or logical.
• IDEs like Dev C++ simplify the process of coding and debugging.
• The basic C++ syntax always includes:
  • Header (#include)
  • Main function (int main())
  • Output statement (cout)
  • Return statement (return 0;)