Introduction to C++

SDSLabs

- Satyam Vijay - Abhinav Tushar

What this lecture is all about?

A very basic primer of computer programming using C++ language

Why should you learn programming ?

Why should you learn programming ?

Programming is Automation

Programming teaches you how to break problems

It’s a way to create change

Programming is fun

Why C++ ?

Powerful and fast

It will provide you a better understanding of other systems

** You will hardly be seen as a hacker if you don’t know C++ **

Getting your machines ready

variables

Store values.

data type variable = value;

int x = 34;

Naming Conventions

• Must start with an alphabet or underscore "_"
• May only be comprised of alpha-numeric characters and underscores. a-z, A-Z, 0-9, or _
• Cannot use reserved words (keywords), like 'int', 'while' etc as identifiers.

Operators

• Assignment Operators
• Arithmetic Operators
• Comparison Operators

Assignment Operator=

    int a = 5;
    char b = 'h';

Arithmetic Operator

• Addition: +
• Subtraction: -
• Division: /
• Multiplication: *
• Modulus: %

Comparison Operator

• Equal To: ==
• Not Equal To: !=
• Less Than: <
• Greater Than: >
• Less Than or Equal To: <=
• Greater Than or Equal To: >=

The Console

outputting and inputting values

using cout and cin

    #include<iostream>

Cout

prints values to console

    cout << "Hello";
          	

    int x = 5;
    cout << "Hello, x = " << x;
          	

Cin

takes user value from console and saves it to a variable

    int number;
    cin >> number;
    int twice_of_number = number * 2;
    cout << twice_of_number;
          	

System Pause

Pauses the console until a key is presed

    cout << "Sample Output";
    system("pause");
            

Special case for devcpp

Conditional statements

if, if-else & switch

if

  int marks = 100;
  if (marks==100)
    cout << "Congrats !! Chapo.";

if-else

  int marks = 88;
  if (marks==100)
    cout << "Congrats !! Chapo.";
  else
    cout << ":|";

switch

  switch (x) {
  case 1:
    cout << "x is 1";
    break;
  case 2:
    cout << "x is 2";
    break;
  default:
    cout << "value of x unknown";
  }

arrays

Lots of values in one parent variable

Remember indexed values ?? Maths

the elements collectively are called an 'array' of elements

creating arrays

data type array[length]

  int arr[3];
  arr[0] = 34;
  arr[1] = 54;
  arr[2] = 13;
  

  int arr[3] = {34, 54, 13};
  

accessing array members

array[index]

  char y = 'c';
  char array[4] = {'a', 'b', 'f', 'd'};
  array[2] = y; // now array is {'a', 'b', 'c', 'd'}
  

loops

For, While, Do While

For Loop

  for (initialize; conditional statement; update){
     do this code;
  }
  

  int years[4] = {2002, 2007, 2010, 2013};

  for (int i = 0; i < 4; i++){
  	 cout << years[i] << "\n";
  }
            

While Loop

  while (conditional statement is true) {
    //do this code;
  }
  

  int years[4] = {2002, 2007, 2010, 2013};

  int i = 0;
  while(i<4){
  	 cout << years[i] << "\n";
  	 i += 1;
  }
            

Do While

  int years[4] = {2002, 2007, 2010, 2013};

  int i = 0;
  do{
  	 cout << years[i] << "\n";
  	 i += 1;
  }
  while(i < 4);