C Basics Workshop

SLIDES

CHALLENGES

Caleb's C tutorials

Ruby Original Code

Installation

Check if they can run the cc or gcc commands.

Introduction: A little bit of History / What about A & B ?

The C programming language was created by Dennis Ritchie in 1972, it was first designed to be an internal language for the company he worked for: Bell laboratories.
The transition of C to open source was a gradual process until the early 1990's.
There were no "A" programming, but B was indeed a precursor to C. B was derived from BCPL (Basic Combined Programming Language)
C was initially created for internal use at Bell Laboratoies, C offered a good balance between high-level abstraction and low-level control
C's combination of portability, efficiency, and support for structured programming made it revolutionary and paved the way for modern systems programming languages.

Low level vs high level / C vs Ruby

high-level programming languages prioritize ease of use, while low-level programming languages offer more direct control
Examples of languages of various levels:

Low-Level Programming Languages:
- Assembly Language: Assembly languages are specific to a particular computer architecture and are essentially a symbolic representation of machine code instructions.
- C: While C is often considered a mid-level language, it is also quite low-level because of its close relationship with the hardware, providing features like direct memory manipulation and pointer arithmetic.
- Machine Code: This is the lowest level, consisting of binary instructions directly executable by the CPU.
Mid-Level Programming Languages:
- C++: Building upon C, C++ introduces object-oriented programming features while maintaining compatibility with C.
- Java
- Python: Python is considered mid-level because it offers high-level abstractions while still allowing some control over low-level details. It's known for its simplicity and readability.
High-Level Programming Languages:
- JavaScript: Often used for web development, JavaScript is a high-level language that runs in web browsers, providing dynamic functionality to web pages.
- Ruby: Known for its simplicity and productivity, Ruby is a high-level language commonly used for web development and scripting.
- Swift: Developed by Apple, Swift is a high-level language used for iOS, macOS, watchOS, and tvOS app development. It's designed to be modern, safe, and expressive.

Ruby

Ruby was created by Yukihiro Matsumoto (Matz) and released in 1995. It's known for its simplicity and productivity, often used for web development, scripting, and other applications. The Matz's Ruby Interpreter (MRI), which is the original Ruby interpreter, which executes Ruby code is implemented in C. The core functionality of Ruby is written in C code.

Writting our first program in C "Hello World!"

note: Exercie in folder 1-HelloWorld

In C, you have to explicitly define a main function as the entry point, whereas in Ruby, you directly write your code.
C requires manual compilation using a compiler like cc (C compiler), whereas Ruby doesn't require compilation as it's an interpreted language (where compilation is done automatically).
```
cc hello.c -o hello
```
C gives you finer control over system resources, we'll talk about that later.

User interface in the terminal: scanf vs gets.chomp

note: Exercie in folder 2-PrintName

Data types (the main ones)

note: Exercie in folder 3-DataTypes

int: Used to store integers (whole numbers), typically with a size of 4 bytes on most systems.
char: Used to store single characters, typically 1 byte in size.
float: Used to store floating-point numbers (numbers with decimal points), typically with a size of 4 bytes.
double: Similar to float but with double precision, typically with a size of 8 bytes.
long int / long long (respectively 2,147,483,647 and 9,223,372,036,854,775,807, which is almost 10 quintillion)
_Bool: Used to store boolean values (true or false), typically 1 byte in size.
void: Used to indicate that a function does not return any value or to indicate a pointer to some unspecified type.

#include <stdio.h>

int main() {
    int integerVar = 42;
    float floatVar = 3.14;
    char charVar = 'A';
    char stringVar[] = "Hello, World!";

    printf("Integer: %d\n", integerVar);
    printf("Float: %f\n", floatVar);
    printf("Character: %c\n", charVar);
    printf("String: %s\n", stringVar);

    return 0;
}

⚠️ %d is a standard format specifier in C for printing integers as well as %i. The d stands for decimal integer.

Function declaration (with data type specification)

note: Exercie in folder 4-DeclaringFunctions

In this section we introduce 2 concepts related to function declaration and data type handling:
- Functions are declared specifying the data type they are supposed to return
- If Functions require parameters, their data type also need to be specified
- Introduction to void.

Conversion functions (to_s, to_i, to_f)

note: Exercie in folder 5-Converters

To string

int num = 12;
char str[20];
sprintf(str, "%d", num);

To integer: atoi() (ASCII to Integer)

#include <stdio.h>
#include <stdlib.h>

int main() {
  char str[] = "1485";
  int num = atoi(str);
  printf("%d\n", num);
  return 0;
}

To float: (float)num

#include <stdio.h>

int main() {
  int num = 12;
  float fnum = (float)num;
  printf("%f\n", fnum);
  return 0;
}

The ASCII way of converting from String to Integer and vice versa:

#include <stdio.h>

 int main() {
   char num = '6';
   int conv_num = num - '0';
   printf("%d\n", conv_num);
   num = conv_num + '0';
   printf("%c\n", num);
   return 0;
 }

In addition to conversion functions, there are functions that checks the data type of a variable. There are NO functions is C that return the datatype of an element such ay typeof in javascript, or .class in Ruby. See 5-Converters/isalpha.c file.

Built-in functions in C

note: Exercie in folder 6-BuildInFunctions -> strlen.c and strcmp.c files

Here are a few examples of commonly used in-built functions:

printf()
strlen()
atoi()
strcmp(): This function is used to compare two strings. It returns 0 if the strings are equal, a negative value if the first string is lexicographically less than the second, and a positive value if the first string is lexicographically greater than the second.

Live Code: .even?

note: Exercie in folder 7-EvenOrOdd

Introduciton to the if statement:

if (condition)
{
  // // code to execute
}
else
{
  // code to execute
}

Strings & Pointers

note: Exercie in folder 8-Pointers

Strings are similar to an Array of characters and contain end with a Null terminator
Each character is made of 8 bits which corresponds to 1 byte of memory (Integers represent 4 bytes of memeory)
- See: defining_a_string.c
- char str[100]; is a variable déclaration. This syntax stores the data in the stack memory, which is accessed during compilation of the code. The allocation and deallocation are managed automatically by the compiler.
- char *str; is a pointer déclaration. The pointer points to memory location of the first character of the string. This is stored in the heap, which is a region of memory used for dynamic memory allocation. You manually need to allocate and free (deallocate) the memory.
A pointer is a variable that stores the memory address of another variable
- See: pointer.c

Livecode: donwcase / upcase

note: Exercie in folder 9-SimpleDowncase

Introduction to the while loop

int i = 0;
while(i < 10)
{
   // code to execute
   i++; // incrementation
}

Introduction to the ASCII table (American Standard Code for Information Interchange)
```
man ascii
```
Illustration with the simple-downcase.c challenge.

Memory allocation (optional)

note: Exercie in folder 8-Pointers using the syntax char *str = (char *)malloc(sizeof(char) * 100); and adding free(str) at the end.

malloc allocates memory dynamically during runtime, while free deallocates previously allocated memory, preventing memory leaks and managing memory efficiently.
Illustration with the malloc_and_free.c challenge.

note: Exercie in folder 10-MemoryAllocation takes it one step further.

Challenges

Challenges on Notion

OGsoundFX/C-Workshop