Lecture: Getting Started with C Programming 💻

Introduction

• C is a middle-level programming language from the 1970s.
• It's widely used: efficient like low-level languages, but more abstract like high-level languages.
• Influential: many languages are based on C (e.g., Python's default implementation is CPython).
• Not object-oriented (procedural).

Tools Needed

1. IDE (Integrated Development Environment)
   • Recommended: VS Code.
2. GNU Compiler Collection (GCC)
   • Used to compile C code to machine code.

Setting Up VS Code for C Programming

1. Go to code.visualstudio.com to download VS Code.
2. Install extensions:
   • C/C++ for intellisense.
   • Code Runner to run code.
3. Create a C file:
   • Create a new folder for your project.
   • Inside the folder, create a file with a .c extension (e.g., helloworld.c).

Installing GCC

• Windows: Check if GCC is installed via g++ --version in command prompt.
  • If not installed, download and set up MinGW from SourceForge link.
• Mac: clang --version. If not installed: xcode-select --install.
• Linux: gcc -v and install using sudo apt-get install build-essential.

Configure Build Tasks in VS Code

1. Open VS Code terminal.
2. Configure default build task: terminal -> configure default build task -> C++ (G++ Task).
3. This generates a tasks.json file within .vscode that tells VS Code how to compile the program.

Writing Your First C Program

1. Include necessary headers: #include <stdio.h>.
2. Write a main function:

   int main() {
       printf("I like pizza\nIt's really good");
       return 0;
   }
   

3. Compile and run the program using run code or manually via terminal.

Handling Errors in C

• Ensure proper syntax: missing semicolons or wrong function names will cause errors while compiling.
• Error example: Misspelling printf as just print.

User Input in C

• Switch from output tab to terminal to accept user input.
• Use scanf for simple inputs or fgets for strings that may contain whitespaces.

  // for integers
  int age;
  printf("How old are you?");
  scanf("%d", &age);
  printf("You are %d years old", age);
  

  // for strings with white spaces
  char name[25];
  printf("What is your name?");
  fgets(name, 25, stdin);
  name[strlen(name) - 1] = '\0'; // removes newline
  

Writing and Compiling C Programs

• Save your C file and run it from the terminal to see outputs or debug errors.

Comments and Escape Sequences

• Comments: // for single-line, /* */ for multi-line.
• Escape Sequences: \n for newline, \t for tab, \" for quotes, \\ for backslash.

Using Variables in C

• Variables must be declared before use.
  • Basic types: int, float, char, arrays, etc.
  • Example: int age = 21;
• Using format specifiers in printf to display variables.

Logical Operators

• AND (&&): Checks if multiple conditions are true.
• OR (||): Checks if at least one condition is true.
• NOT (!): Reverses the state of a condition.

Functions in C

• Function declaration and calling.

  void birthday() {
      printf("Happy Birthday!");
  }
  
  int main() {
      birthday(); // calling the function
      return 0;
  }
  

• Arguments and Parameters: Pass values to functions.
• Return Statement: Return values from functions.
• Function prototypes: Ensure calls to functions are made correctly.

Working with Arrays

• Declaration: int numbers[5];
• Initialization: int numbers[] = {1, 2, 3, 4, 5};
• Accessing elements using index numbers starting from 0.
• Iterating arrays using loops.
• Multidimensional arrays (e.g., 2D arrays).

Structs in C

• Creating structs to group related variables under one name.

  struct Player {
      char name[50];
      int score;
  } player1, player2;
  

• Access struct members using the dot operator.
• Typedef: Giving a new name to an existing type (e.g., typedef struct Player Player;).

Enumerations

• Use enum keyword to create a type with named integer constants.

  enum Day {SUN, MON, TUE, WED, THU, FRI, SAT};
  enum Day today = MON;
  

Pointers in C

• Pointers store memory addresses of variables.
• Declaration: int *p = &var;
• Dereferencing pointers: *p
• Useful for passing large variables to functions, dynamic memory allocation, etc.

File Operations

• Writing to a file: Use `FILE *fp = fopen(