CS50x 2026 - Lecture 1 - C | CS50

This CS50 lecture introduces fundamental programming concepts in C, drawing parallels to the earlier Scratch-based lessons. It highlights the transition from graphical puzzle pieces to text-based source code, emphasizing that the underlying logic remains consistent. The lecture details the roles of source code, machine code, and compilers in translating human-readable instructions for computers. It covers essential C syntax, including functions (printf, getString), variables, data types (int, char, string), operators, conditionals (if/else), and loops (for, while). The lecture also emphasizes good coding practices, like design, style, and correctness, and introduces tools like Check50, Design50, and Style50. Real-world implications of programming limitations, such as integer overflows, are discussed, using examples like the Boeing 787 software counter issue.

Outlines

Part 1: Introduction, Environment Setup

Part 2: Libraries, Input, Linux CLI

Part 3: Logic, Data Types, Design

Part 4: Loops, Functions, Structures

Part 5: Hardware Limitations, Real-world Bugs

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CS50x 2026 - Lecture 1 - C

CS50

Part 1: Introduction, Environment Setup

Introduction to CS50 Week 1: Transitioning from Scratch to C Programming

Setting Up and Using VS Code for C Programming: GUI, CLI, and Basic Commands

Writing and Troubleshooting a Simple "Hello, World" Program in C

Part 2: Libraries, Input, Linux CLI

Libraries, Header Files, and CS50's Manual Pages for C Programming

Using CS50's getString Function for User Input and Variable Assignment

Printing User Input with Placeholders and Understanding Header File Locations

Introduction to Linux Commands: File Management via CLI

Part 3: Logic, Data Types, Design

Conditionals in C: Translating Scratch Logic with If, Else If, and Else

Data Types in C: Booleans, Characters, Floats, Doubles, and Integers

Variables and Increment Operators in C: Implementing a Counter

Code Design Principles: Avoiding Redundancy and Inefficiency

Part 4: Loops, Functions, Structures

Character Input and Looping: Creating an Agree Program with Error Handling

Code Style and Scope: Creating a Reusable Meow Function

Building a Text-Based Mario Game: Loops and Two-Dimensional Structures

Part 5: Hardware Limitations, Real-world Bugs

Calculator Limitations: Integer Overflow and the Boeing 787 Bug

Floating Point Imprecision and the Year 2038 Problem

CS50x 2026 - Lecture 1 - C

CS50

Part 1: Introduction, Environment Setup

00:00Introduction to CS50 Week 1: Transitioning from Scratch to C Programming

Introduction to CS50 Week 1: Transitioning from Scratch to C Programming

04:13Setting Up and Using VS Code for C Programming: GUI, CLI, and Basic Commands

Setting Up and Using VS Code for C Programming: GUI, CLI, and Basic Commands

09:09Writing and Troubleshooting a Simple "Hello, World" Program in C

Writing and Troubleshooting a Simple "Hello, World" Program in C

Part 2: Libraries, Input, Linux CLI

17:09Libraries, Header Files, and CS50's Manual Pages for C Programming

Libraries, Header Files, and CS50's Manual Pages for C Programming

27:10Using CS50's getString Function for User Input and Variable Assignment

Using CS50's getString Function for User Input and Variable Assignment

35:42Printing User Input with Placeholders and Understanding Header File Locations

Printing User Input with Placeholders and Understanding Header File Locations

44:03Introduction to Linux Commands: File Management via CLI

Introduction to Linux Commands: File Management via CLI

Part 3: Logic, Data Types, Design

55:49Conditionals in C: Translating Scratch Logic with If, Else If, and Else

Conditionals in C: Translating Scratch Logic with If, Else If, and Else

1:02:25Data Types in C: Booleans, Characters, Floats, Doubles, and Integers

Data Types in C: Booleans, Characters, Floats, Doubles, and Integers

1:17:20Variables and Increment Operators in C: Implementing a Counter

Variables and Increment Operators in C: Implementing a Counter

1:28:28Code Design Principles: Avoiding Redundancy and Inefficiency

Code Design Principles: Avoiding Redundancy and Inefficiency

Part 4: Loops, Functions, Structures

1:41:11Character Input and Looping: Creating an Agree Program with Error Handling

Character Input and Looping: Creating an Agree Program with Error Handling

1:55:47Code Style and Scope: Creating a Reusable Meow Function

Code Style and Scope: Creating a Reusable Meow Function

2:06:00Building a Text-Based Mario Game: Loops and Two-Dimensional Structures

Building a Text-Based Mario Game: Loops and Two-Dimensional Structures

Part 5: Hardware Limitations, Real-world Bugs

2:12:24Calculator Limitations: Integer Overflow and the Boeing 787 Bug

Calculator Limitations: Integer Overflow and the Boeing 787 Bug

2:24:02Floating Point Imprecision and the Year 2038 Problem

Floating Point Imprecision and the Year 2038 Problem