CS50 Week 1 Lecture Notes

Introduction

• David Malan introduces CS50 and the focus on the C programming language.
• Emphasis on problem-solving and building a toolkit of programming skills.

Overview of C Language

• Transition from Scratch (week 0) to C, focusing on functions, variables, conditionals, and loops.
• Introduced concepts like source code vs. machine code, and the role of compilers.

Source Code vs. Machine Code

• Source code: what programmers write (in C).
• Machine code: binary (0s and 1s) that computers understand.
• Compiler: translates source code to machine code.

Writing Your First C Program

• Example: "Hello, world" program.
• Boilerplate code: includes headers and main function structure.
• Importance of syntax and indentation in C.

C Syntax

• Functions: printf replaces Scratch's say.
• Variables and data types: int, float, char, etc.
• Control structures: conditionals (if, else) and loops (for, while).

Using the Command Line

• Introduction to using a CLI with commands:
  • ls: list files.
  • mv: move (rename) files.
  • rm: remove files.
  • cd: change directory.

Functions and Return Values

• Functions can return values: int add(int a, int b).
• Example of using functions: adding two numbers and returning the result.
• Scope of variables: a variable's context of existence in code.

Working with Floats and Doubles

• Issue of integer division leading to truncation.
• Use of type casting to handle floating-point numbers correctly.
• Floating point imprecision may occur due to finite memory.

Common Programming Problems

• Integer overflow: when a number exceeds its storage capacity.
• Example: the 2038 problem with 32-bit integers.
• Floating point imprecision: limitations of representing real numbers.

Practical Exercises

• Examples of drawing a grid with loops in C.
• Using do-while loops and while loops effectively.
• Incorporating user input and validation to ensure correct program behavior.

Conclusion

• Encouragement to practice and troubleshoot programming concepts.
• Importance of understanding limitations and ensuring code correctness.
• Upcoming challenge: Problem Set 1.