CS50x 2026 - Lecture 2 - Arrays | CS50

This CS50 lecture explores debugging techniques, the compilation process, and memory representation in C programming. It emphasizes using `printf` and `debug50` to identify logical errors, alongside rubber duck debugging. The lecture demystifies compilation, detailing preprocessing, assembling, and linking, while cautioning against reverse engineering. Data types' memory usage (bool, int, char, string) is explained, visualizing memory as a grid. Arrays are introduced as contiguous memory blocks, improving code design. The lecture also covers command-line arguments via `argc` and `argv`, and the importance of exit statuses for indicating success or failure. It touches on cryptography and the Caesar cipher as an application of these concepts.

Outlines

Part 1: Introduction, Debugging Tools

Part 2: Compilation, Memory, Data Types

Part 3: Arrays, Strings, Libraries

Part 4: Command Line, Cryptography

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CS50x 2026 - Lecture 2 - Arrays

CS50

Part 1: Introduction, Debugging Tools

Introduction to CS50 Week 2: Reading Levels, Strings, and Debugging

Debugging Techniques: Printf Statements and Debug50

Debug50 Demonstration and Rubber Duck Debugging

Part 2: Compilation, Memory, Data Types

From Source Code to Machine Code: The Compilation Process

Reverse Engineering and Limitations of Decompilation

Data Types, Memory, and the Problem with Averaging Integers

Part 3: Arrays, Strings, Libraries

Arrays: A Better Design for Storing Multiple Values

Strings as Arrays of Characters and the Null Terminator

String Length and the String Library

Character Manipulation and the Ctype Library

Part 4: Command Line, Cryptography

Command Line Arguments: Argc and Argv

Introduction to Cryptography: The Caesar Cipher

CS50x 2026 - Lecture 2 - Arrays

CS50

Part 1: Introduction, Debugging Tools

00:00Introduction to CS50 Week 2: Reading Levels, Strings, and Debugging

Introduction to CS50 Week 2: Reading Levels, Strings, and Debugging

18:31Debugging Techniques: Printf Statements and Debug50

Debugging Techniques: Printf Statements and Debug50

27:21Debug50 Demonstration and Rubber Duck Debugging

Debug50 Demonstration and Rubber Duck Debugging

Part 2: Compilation, Memory, Data Types

39:46From Source Code to Machine Code: The Compilation Process

From Source Code to Machine Code: The Compilation Process

55:33Reverse Engineering and Limitations of Decompilation

Reverse Engineering and Limitations of Decompilation

1:01:45Data Types, Memory, and the Problem with Averaging Integers

Data Types, Memory, and the Problem with Averaging Integers

Part 3: Arrays, Strings, Libraries

1:17:17Arrays: A Better Design for Storing Multiple Values

Arrays: A Better Design for Storing Multiple Values

1:27:20Strings as Arrays of Characters and the Null Terminator

Strings as Arrays of Characters and the Null Terminator

1:38:38String Length and the String Library

String Length and the String Library

1:53:55Character Manipulation and the Ctype Library

Character Manipulation and the Ctype Library

Part 4: Command Line, Cryptography

2:07:04Command Line Arguments: Argc and Argv

Command Line Arguments: Argc and Argv

2:20:22Introduction to Cryptography: The Caesar Cipher

Introduction to Cryptography: The Caesar Cipher