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Monday, 30 March 2015

Begginer's Guide to C++- Chapter 1: Introduction to C++

This is the first chapter to a long upcoming series, aimed at making you all learn C++, in quite an easy and fun way. You will be able to learn almost all concepts, without getting tired or bored.

We will be using Turbo C++ compiler for the proceedings. You can search for this "Turbo C++ by Neutron", it will get you to a ready to install package. Also, some programmers will say that the conventions, along with the compiler that I use are outdated, and programming has become much more liberal, but I think that developing your skills on any compiler is fine and, you will learn to modify it, to suit other compilers. What is important is to learn to think like a programmer and break your objective into smaller targets/modules. Through my guide, you will learn just that!

C++ is a case-sensitive language, i.e. the words “doctor”,  “Doctor” and “DoCtOr” will be recognised as different by the compiler, so make sure you keep that in mind.

Basic Terminologies:
  1. Keyword: These are the commands that the compiler understands. Thus these are special words that make the compiler do certain things.
  2. Variable/Identifier: These are storage locations, eg. x=5, where x is called the variable (just like mathematics).
  3. Operator: +,-,*,/ etc. Nothing worthy to explain about them, they do what their symbol suggests.
  4. Datatypes: These are a way to specify the kind of variable you are making. Eg- int - integer, char - character.

Rules for naming variables:
  1. It should not be a keyword.
  2. It should not have any special character like ' ', '*', etc. However, '_' is allowed while naming.
  3. The name should not begin with a number.

Operators: The following operators are available in C++,
Algebraic Operators:
1. +,-,*,/...
2. % - It finds the remainder from 2 numbers. Eg- 3%2 will give answer as 1.
      32%10 will give answer as 2.
Conditional/Relational Operators: Used to check conditions.
3. <,>,<=,>=...
4. == - Used to check equality. Consider this statement as "Is this equal?". If you write x==3, you are asking " Is x equal to 3?". I will elaborate on this later, when its use comes up.
Logical Operators:
5. && - And operator, used to join 2 statements with "and". It is just like the usage in English - "I want to eat mangoes and apples." Here we need both apples and mangoes to be given, in order for me to eat them.
6. || - Or operator, used to join 2 statements with "or". It is also used similar to the way we use it normally - "I want to eat mangoes or apples". Here we need at least an apple it a mango, or even both for me to eat them.
7. ! - Not operator, negates the current input. Eg- != will check if two given values are not equal.
Increment and Decrement Operators:
8. ++ - Adds 1 to the variable's value. Eg- If a variable p is equal to 10, p++ will make it equal to 11.  You can write it both as p++ and ++p, it does not matter.
9. -- - Similar to the above operator, but instead subtracts 1 from variable's value.

Datatypes: Datatypes are of the following types:
  1. int- Used to define integer type variables. Range- -32768 to 32767.
Syntax- int variablename;
  1. float- It is used to define a variable with decimal values. Eg- 10.43. Range- 3.4E +/- 38.
Syntax- float variablename;
  1. double- It is similar to float, but it has a greater range. Range- 1.7E +/- 308.
Syntax- double variablename;
  1. char- It declares a character type variable. Characters are enclosed in ‘’ (Single quotes), and are also represented by ASCII Codes. ASCII codes range from - -128 to 127.
Syntax- char variablename;
  1. void- It denotes an empty set of values. I will explain it later. No variable of this type can be declared.

Special Characters: There are some characters that represent a special meaning. Some are as follow -
  • /n - New Line
  • /t - Tab
  • /a - CPU beep sound
  • /' - Prints '
  • /" - Prints "
                            
Rules for variable declaration:
Syntax:
datatype variablename1,variablename2;
You can also initialize a variable by a value while declaring it.
Eg.- int x=10; (initializes an integer variable and designates its value as 10)
There is one rule of thumb, that you must always remember- You can initialize 1 and only 1 variable while defining it. This means you can provide value to only 1 variable while declaring.
Eg- int x=10,y=20;   is invalid
      int x=10,y;          is valid
      int x=y=10;         is invalid
We always write a=b+c; to store the value of b+c in a. b+c=a is wrong, and the compiler will report an error. Eg- It is always "Tom plays a guitar" rather than "Guitar plays a Tom".



Comments:
Comments help in noting down what statement serves what purpose. They are of two types-
  1. Single Line - For writing a single line comment, first put a “//” and then write the comment. Eg- int x=10; //Initializing x
  2. Multiline - Multiline comments begin by “/*” and end at “*/”.
Eg- /* Hey, howdy?
This is a multi-line comment
I hope you understood the concept*/

So friends, I take my leave here. Please go over the article again, and try to memorize the whole thing because these are the most basic and fundamental concepts in C++, and you will need them at every step.

About The Author
Rajat is a coding enthusiast, with an explicit interest in reading and gaming. He is the admin of this blog and is currently working on increasing the reach of the blog. He is called "Dr. Sheldon Cooper" by his coworkers, but extraordinary is the fact that he does not know who Sheldon is! Follow him on .