Elzero Web School

Elzero Web School

C++ Course

003 - Install Visual Studio Code, Debugger And Compiler

pacman -Syu
pacman -Su
pacman -Ss gcc
pacman -S mingw-w64-x86_64-gcc
pacman -Ss gdb
pacman -S mingw-w64-x86_64-gdb

gcc --version
g++ --version
gdb --version

#include <iostream>

int main()
{
  std::cout << "Iam Here";
  return 0;
}

008 - Comments And Use Cases

// Include Iostream
#include <iostream>

/* Elzero */

// This Is Main Function
int main()
{
  std::cout << "Line 1\n"; // Comment
  std::cout /* <= This Is Character Out */ << "Line 2\n";
  std::cout << "Line 3\n";
  // Comment
  std::cout << "std::cout";
  return 0;
} // Comment

// Search Google For "Iostream"

// ========== Elzero ========== //

//////////// Elzero ////////////

/*
  ==================
    Elzero
  ==================
*/

/*==================
    Elzero
  ==================*/

009 - Variables Basic Knowledge

Variables Basic Knowledge

Data Container With Unique Name "Identifier"
Declare With Value + Change Later

Syntax

[Data_Type] [Variable_Name] = [Value]

#include <iostream>
using namespace std;

int main()
{
  int price = 200;
  cout << "Price Is: " << price;
  cout << "\nPrice After Adding 15 Is: " << price + 15;
  cout << "\nPrice After Adding 50 Is: " << price + 50;
  price = 150;
  cout << "\nThe New Price Is: " << price;
  return 0;
}

010 - Variables Naming Rules And Best Practices

Naming Rules -- Must Be Unique -- Case Sensitive -- Cannot Start With Numbers -- Nums Or Letters Or Underscore -- No White Space Or Special Characters -- Reserved Keywords "Class, Public"
Best Practices -- Related Names -- Writing Style

#include <iostream>
using namespace std;

int main()
{
  int price = 100; // Declare A New Variable
  price = 200;     // Update The Value
  int Price = 400;
  cout << price;
  cout << "\n===============\n";
  int n1um1111 = 10;
  cout << n1um1111;
  cout << "\n===============\n";
  int _num_bers_ = 100;
  cout << _num_bers_;
  cout << "\n===============\n";
  int publics = 1000;
  cout << publics;
  cout << "\n===============\n";
  int OSAMA = 500; // Bad Style
  cout << OSAMA;
  cout << "\n===============\n";
  int x = 1000;
  cout << x;
  return 0;
}

011 - Variables Advanced Knowledge

Variables Advanced Knowledge -- Declare Variable Without Value + Change Later -- Declare Multiple Variables Without Value + Change Later -- Declare Multiple Variables With Same Value

#include <iostream>
using namespace std;

int main()
{
  int a;
  a = 100;
  cout << a; // 100

  cout << "\n================\n";

  int b, c, d;
  b = 10, c = 20, d = 30;
  cout << b + c + d; // 60 => [10 + 20 + 30]

  cout << "\n================\n";

  int e, f = 40, g;
  e = 20, g = 60;
  cout << e + f + g; // 120

  cout << "\n================\n";

  int h, i, j;
  // h = 10, i = 10, j = 10;
  h = i = j = 10;
  cout << h + i + j; // 30

  return 0;
}

012 - Variables Scope

Variables Scope -- Global Variable -- Local Variable

#include <iostream>
using namespace std;

int a = 100; // Global Variable

int second()
{
  int b = 200; // Local Variable
  cout << a << " Coming From Second Function\n";
  cout << b << " Coming From Second Function\n";
  return 0;
}

int main()
{
  cout << a << " Coming From Main Function\n";
  // cout << b << " Coming From Main Function\n"; // Undefined
  second();
  return 0;
}

013 - Variables – Constant Variable

Constant Variable -- Read Only Value -- Can't Declare Without Value

#include <iostream>
using namespace std;
#define DAYS 9

int main()
{
  const int day = 8;
  // int salary = 15000;
  const int num = 100;
  // num = 200;
  cout << num;
  // const int x;
  cout << "\n" << DAYS;
  return 0;
}

014 - Calculate Your Age Application

#include <iostream>
using namespace std;

int main()
{
  cout << "====================================\n";
  cout << "== Calculate Your Age Application ==\n";
  cout << "====================================\n";

  int age;
  cin >> age;

  int age_in_days = age * 365;
  int age_in_hours = age_in_days * 24;

  cout << "Age In Days Is: " << age_in_days << " Days\n";
  cout << "Age In Hours Is: " << age_in_hours << " Hours\n";

  return 0;
}

015 - Escape Sequences Characters

Escape Sequences Characters

Special Non Printing Characters
Control Printing Behaviour
Start With Back Slash ""
Can Be Inserted In Any Position
Chars: -- \n -- \ -- " -- ' -- \t => Tab Equal 8 Spaces -- \b => Backspace -- \a => Alert => Play Beep During Execution -- \r => Carriage Return

#include <iostream>
using namespace std;

int main()
{
  cout << "Line 1\n";
  cout << "Line 2\n";
  cout << "Line 3\\\n";
  cout << "Line \"4\"\n";
  cout << "Line 5\n";
  cout << "Line\t6\n";
  cout << "Line\b7\n"; // Lin7
  cout << "Line 8\a\n";
  cout << "Osama\rLzero\n"; // Lzero
  cout << "Line"; // This Is Line \\
  return 0;
}

016 - Data Types – What Is Data ?

Data Types

What Is Data ?
Data Examples In Real Life
- Integer => 5000, 10, -100
- String => "Elzero Web School", "Osama Elzero", "100A"
- Boolean => true, false
- Float => 18.5, 1900.50
- Array => ["Osama", "Ahmed", "Sayed", "Mahmoud"]
Why We Choose Data ?
- Size
- Operation
What Is Operand ?
- The Part Of an Instruction Representing The Data Manipulated by The Operator
sizeof(num) get size in bytes

 cout << sizeof(num)

017 - Data Types, Sizes And Memory

Data Types

Ram [R]andom [A]ccess [M]emory
- Computer Memory Has Locations
Data Sizes
- Bit => [Bi]nary Digi[t] => Smallest Unit in Storage Store Only 0 Or 1
- Byte => A Group of 8 => Store Single Character
- Kilo Byte => 1024 Byte
- Mega Byte => 1024 Kilobytes
- Giga Byte => 1024 Megabytes
- Tera Byte => 1024 Gigabytes
Data Types With Size
- int => 2 Or 4 Bytes => Will Cover Later Why
- float => 4 Bytes [18.5656565656]
- double => 8 Bytes [18.5656565656]
  - Number . Fractional Component
- char => 1 Byte => "A" "x" "9"
- boolean => 1 Byte => true, false
Double vs Float
The Story Behind Creating A Variable
- Declare A Variable
- Tell Computer That We Need To Reserve X Bytes Of Memory Depend On Data Type
- Restrict Type Of Data To The Type We Choosed
Declare Variable Without Type
See Memory Address &
Compiler can deduce the type of data

auto num = 10;

Quiz

Application To Create
- Create App Ask You To Type Number Of Kilobytes
- Write 3 Lines Contains
  - [1] The Number Of Kilobytes That User Input
  - [2] The Number Of Bytes
  - [3] The Number Of Bits

#018 - Data Types - Integer

Primitive Data Types

int => Integer
- Test Numbers
- Test Floating Point vs Int
- Store From -2147483648 To 2147483647
- INT_MIN and INT_MAX Constants
- Check Limits Header File limits.h
- Test Size Of Data Types Without Variables & Use End Line
= Assignment Operator

 #include <limits.h>
..
 cout << INT_MIN << endl;
 cout << INT_MAX << endl;

#019 - Data Types - Float And Double

Primitive Data Types

float => Floating Point Number
- Test Integer Value In Float Variable
- We Make Sure Its Float Not Double By Adding Suffix "f" Or "F"
- Test With Auto
- 7 Decimal Precision
double => Double The Float
- 15 Decimal Precision

#include <iostream>
using namespace std;

int main()
{
  int num = 10;
  num = 20.5;
  cout << sizeof(num) << endl; // 4
  cout << num << endl;         // 20

  double dob = 10;
  dob = 20.5;
  cout << sizeof(dob) << endl; // 8
  cout << dob << endl;         // 20.5

  float fl = 10.5f + 9.5f;
  cout << sizeof(fl) << endl; // 4
  cout << fl << endl;         // 20

  auto mix = 10.f;

  return 0;
}

#020 - Data Types - Char And ASCII

Primitive Data Types

char => Character
- Added Inside Single Quotes => Test With Auto
- ASCII Value
- ASCII => American Standard Code for Information Interchange.
- A Way of Representing Characters As Numbers
Search For Type Casting
Create App To Convert ASCII To Character
Create App To Convert Character To ASCII
Note that 'A' differ from "A"
- 'A' is single char
- "A" is list of char

#include <iostream>
using namespace std;

int main()
{
  char a = 'A';
  cout << sizeof(a) << "\n"; // 1

  auto c = "C";
  cout << sizeof(c) << "\n"; // 8

  char d = 'Z';
  cout << int(d) << "\n"; // 90

  cout << int('%') << "\n"; // 37

  // cout << int("Z") << "\n"; // Error

  cout << char(81) << "\n"; // Q

  return 0;
}

#021 - Data Types - Bool And Void

Primitive Data Types

bool => Boolean
- Only Two Possible Values [true, false]
- Value Is Case Sensitive
- When We Use Boolean Values
  - Anything Has On/Off, Yes/No, True/False
- Test Boolean In Math
- Test > And <
- Test Data [100, 0, -100, ""]
void => Valueless
- Without Value

022 - Data Types – Modifiers And Type Aliases

Primitive Data Types

Modifiers
- Modify The Length Of Data => See Limits
- ٍSigned [int, char]
  - Store Positive, Negative Integers And 0
  - int Is Signed By Default
- Unsigned [int, char]
  - Store Positive Only
- Short [int]
  - Can Be short Instead of short int
- Long [int, double]
  - Store Maximum Value
  - Can Be long Instead of long int
Type Alias
- using identifier = type;
- typedef unsigned long UL;

#include <iostream>
#include <limits.h>
using namespace std;

int main()
{
  int age = 300;
  cout << sizeof(age) << "\n"; // 4 Bytes

  short int new_age = 300;
  cout << sizeof(new_age) << "\n"; // 2 Bytes

  short last_age = 300;
  cout << sizeof(last_age) << "\n"; // 2 Bytes

  cout << sizeof(short int) << "\n";
  cout << sizeof(short) << "\n";
  cout << sizeof(long int) << "\n";
  cout << sizeof(long) << "\n";
  cout << sizeof(long long int) << "\n";
  cout << sizeof(long long) << "\n";

  int num_one = 100;
  cout << num_one << "\n";

  signed int num_two = 0;
  cout << num_two << "\n";

  unsigned int num_three = 100;
  cout << num_three << "\n";

  // unsigned int num_four = -10; // Problem
  // cout << num_four << "\n";

  // using bignum = long long int;

  typedef long long int bignum;

  bignum my_number = 100010001000;
  cout << my_number << "\n";

  return 0;
}

023 - Data Types - Type Conversion

Data Types

Type Conversion
- Convert Data of One Type To Another
Implicit Conversion
- Conversion Is Done Automatically By The Compiler
Explicit Conversion AKA Type Casting
- Conversion Is Done By The Programmer
Data Loss
- When Larger Type Is Converted To Smaller Type
Cast c to be int
- int(c)
  - function like casting
- (int)c
  - casting

024 - Operators - Arithmetic Operators