Welcome to CS103! This lecture will introduce you to the fundamental concepts of programming and set the stage for our journey into C++.
Instructor: Dr. Debasish Pattanayak
Programming is giving computers instructions to solve problems. It involves algorithms (step-by-step solutions), syntax (language rules), logic (reasoning), and debugging (fixing errors).
Programming is the process of creating a set of instructions that tell a computer how to perform a task. These instructions are written in a specific language that the computer can understand. Essentially, you are giving a computer a recipe to follow, a precise sequence of steps to achieve a desired outcome. Without programming, computers are just inert machines; it's the code that brings them to life and enables them to perform countless tasks, from simple calculations to complex simulations.
Key concepts fundamental to programming:
Computers are deterministic machines that follow instructions precisely and predictably.
// Deterministic example:
int result = 5 + 3; // Always equals 8Understanding how computers work is essential for effective programming. At their core, computers are deterministic machines that process information through a series of predictable, logical operations.
Programming is fundamentally a deterministic process. This means that given the same input and conditions, a computer program will always produce the same output. There's no randomness or unpredictability in how computers execute instructions - they follow your code exactly as written, every single time.
This deterministic nature is both a strength and a responsibility - your programs will do exactly what you tell them to do, so precision in your instructions is crucial.
Programming languages evolved from machine code (0s and 1s) to human-readable high-level languages.
From early, cumbersome machine code to the sophisticated, human-friendly languages of today, programming has undergone a remarkable evolution, driven by the need for greater abstraction, efficiency, and problem-solving capabilities.
A look at the trade-offs between performance and abstraction.
// High-Level (C++)
int sum = 5 + 10;
// Low-Level (Conceptual Assembly)
MOV AX, 5
ADD AX, 10The distinction between high-level and low-level languages is crucial for understanding how software interacts with hardware and for choosing the right tool for a given task.
; Add two numbers
MOV AX, 5
MOV BX, 10
ADD AX, BX// Add two numbers
int a = 5;
int b = 10;
int sum = a + b;The classic "Hello, World!" demonstrates the basic structure of a C++ program.
#include <iostream>
int main() {
std::cout << "Hello, World!" << std::endl;
return 0;
}Let's start with the classic "Hello, World!" program in C++. This simple program is traditionally the first program learned in any language, as it demonstrates the basic structure and how to produce output. It will print the text "Hello, World!" to the console.
#include <iostream> // Allows input and output operations.
int main() { // The entry point of the program.
std::cout << "Hello, World!" << std::endl; // Prints to the console.
return 0; // Indicates successful execution.
}Explanation: #include , int main(), std::cout, <<, "Hello, World!", std::endl, and return 0; are the key components.
You need a compiler (like G++) to turn your .cpp code into an executable program.
Example Compilation:
# Compile the code
g++ hello.cpp -o hello
# Run the program
./helloTo write, compile, and run C++ programs, you'll need a C++ compiler and a text editor or Integrated Development Environment (IDE). The compiler translates your human-readable C++ code into machine code that your computer can execute.
hello.cpp.g++ hello.cpp -o hello./hello (on macOS/Linux) or hello.exe (on Windows).GitHub is a web-based platform for version control using Git. It's essential for managing your code.
C++ offers superior performance, system-level control, and resource efficiency. This makes it vital for:
It also provides a deep understanding of computer architecture and memory management.
Python is incredibly popular, but C++ is still a fundamental language to learn, especially in a course like CS103. The answer lies in C++'s unique strengths and its role in foundational computing.
A systematic approach to tackling programming challenges:
// Example: Find the larger of two numbers
// 1. Understand: Compare two integers, return the larger one
// 2. Plan: Use if-else statement for comparison
int findMax(int a, int b) {
return (a > b) ? a : b;
}Effective programming isn't just about knowing syntax - it's about developing a systematic approach to problem-solving. This methodology will serve you throughout your programming journey.
This process becomes second nature with practice and will make you a more effective programmer.
An interactive tool to estimate your programming expertise. This slide is best viewed in normal mode!
Switch back to normal view to try the interactive calculator that measures your programming skills based on languages known, algorithms implemented, and data structures understood.
How do you measure up as a programming expert? Enter your stats below!
(Note: This is just for fun and doesn't reflect actual expertise!)
Comments (// or /*...*/) explain code. Variables are named containers for storing data.
You must declare a variable's type before using it:
// dataType variableName = value;
int score = 100;
double price = 19.99;
std::string playerName = "Alex";
bool isActive = true;As you begin writing your own C++ programs, two fundamental concepts you'll encounter immediately are comments and variables.
//./* and end with */.Variables are named storage locations that hold data. You must declare them with a data type:
int: for whole numbers (e.g., 100).double: for decimal numbers (e.g., 98.6).char: for single characters (e.g., 'A').bool: for true or false.std::string: for text (e.g., "Alice").