Lecture 4: Introduciton to C++

Core Concepts

• Definition: C++ is a high-level, object-oriented, cross-platform programming language developed by Bjarne Stroustrup as an extension of the C language.
• Primary Use: Used to create high-performance applications, giving programmers significant control over system resources and memory.
• Key Characteristics:
  • Object-Oriented: Provides a clear program structure and allows for code reuse.
  • Fast & Efficient: It is a compiler-based language, resulting in faster programs compared to interpreted languages like Python or Java.
  • Portable: C++ source code (.cpp files) can be compiled and run on multiple platforms with few or no changes.
  • Popular: Widely used in operating systems, graphical user interfaces (GUIs), and embedded systems.

Comparison: C vs. C++

Feature	C	C++
Paradigm	Procedural	Procedural & Object-Oriented
OOP Support	Does not support OOP features.	Supports key OOP features.
Core Difference	Lacks concepts like classes, objects, inheritance, polymorphism, and encapsulation.	Developed as an extension of C to include the OOP features that C lacks.
Syntax	Both languages share almost the same basic syntax.

Key Features of C++

• Object-Oriented Programming (OOP): Structures programs efficiently. Key concepts include:
  • Data Abstraction
  • Data Encapsulation
  • Inheritance
  • Polymorphism
  • Data Hiding
• Compiler-Based: A compiler converts C++ source code directly into machine language, making execution fast and efficient.
• Memory Management: Supports dynamic memory allocation using pointers. Programmers must manually deallocate memory after use.
• Pointers: A variable that stores the memory address of another variable, allowing for direct memory interaction.
• Broad Library: Offers a vast standard library of built-in functions, accessed via header files (e.g., <iostream>).
• Operator Overloading: Allows programmers to provide special meanings to operators for specific data types.
• Case Sensitive: Treats uppercase and lowercase letters differently (e.g., cout is not the same as Cout).
• Exception Handling: Provides mechanisms to catch and manage errors that arise during program execution.
• Platform Dependency vs. Portability:
  • Platform Dependent: A compiled C++ program (.exe file) can only run on the operating system where it was compiled.
  • Portable: The C++ source code (.cpp file) can be moved to a different operating system and recompiled to work there.

The C++ Compilation and Linking Process

The process transforms a C++ source file (.cpp) into an executable file (.exe) through several distinct phases.

Phase #	Phase Name	Description	Output File
1	Preprocessing	Handles directives starting with # (e.g., #include, #define).	.i (preprocessed file)
2	Lexical Analysis	Breaks the source code into units called tokens (keywords, identifiers, etc.).	(internal)
3	Syntax Analysis	Checks if the tokens follow the grammatical rules of C++.	(internal)
4	Semantic Analysis	Checks the logical meaning, such as variable declarations and type compatibility.	(internal)
5	Intermediate Code Gen	Generates a machine-independent intermediate representation of the code.	.ir
6	Code Optimization	Improves the intermediate code to make the program faster or use less memory.	(internal)
7	Code Generation	Translates the optimized code into assembly language.	.s (assembly file)
8	Assembly	Translates assembly code into machine-readable object code.	.o (object file)
9	Linking	Combines the object file with necessary libraries to create the final executable.	.exe

Development Tools

• Text Editor: A program for writing plain text code (e.g., Notepad). Requires a separate compiler.
• Integrated Development Environment (IDE): A software suite that combines a text editor, compiler, and debugger into a single application (e.g., Dev C++, Visual Studio, Code Blocks).

Types of Programming Errors

Error Type	When Detected	Description	Example
Compile-time Error	During compilation	A syntax or grammatical mistake in the code. The program will not compile.	Missing a semicolon ;.
Runtime Error	During execution	Occurs while the program is running, often causing it to crash.	Division by zero.
Logical Error	After execution	The program runs without crashing but produces an incorrect or unexpected result.	Using * for multiplication when division / was intended.

Basic C++ Program Structure

Example Code:

#include <iostream>
using namespace std;

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

Syntax Rules & Explanation:

• #include <iostream>: A preprocessor directive that includes the iostream header library, which is necessary for input/output operations.
• using namespace std;: Allows the use of names for objects (like cout) from the standard library without the std:: prefix.
  • Alternative: If this line is omitted, you must use std::cout instead of cout.
• int main() { ... }: The main function where program execution begins. All code inside the curly braces {} is executed.
• cout << "Hello World!";: This is a statement.
  • cout: An object used to print output to the screen.
  • <<: The insertion operator, which sends the data on its right to the object on its left.
  • "Hello World!": A string literal. Text must be enclosed in double quotes. Numbers do not need quotes.
• return 0;: Terminates the main function and indicates successful execution.
• ; (Semicolon): Every C++ statement must end with a semicolon. Omitting it causes a compile-time error.