C Plus Plus programming tutorial (Basics of C++)

PARSED ADSENSE CODE

This tutorial is mainly about theoretical knowledge but is very important!

Some Definitions :

•  Bit : It is the smallest unit a computer can understand. it is either 0 or 1. 0 generally means circuit is OFF and 1 means ON.
• ASCII : All characters on keyboard have a code which is known as ASCII code.
  Range A-Z  ->  65-90
  a-z  ->  97-122
• Byte : Group of 8 bits. 1 byte means 1 character.
• Program : It is a step by step instruction which tell what to do and how to do.
• Object Code : A program which a machine can understand is called Object Program.\

Compiler : 
A program which converts source code[ English like step wise instruction to computer] to object code[language which a machine can understand].
IT executes the entire program at once and hence It is faster.
Interpreter :
A program which converts source code[ English like step wise instruction to computer] to object code[language which a machine can understand]. But the interpreter executes the program line by line and hence it is slower.
Constants : 
Integer Constant :

• Consist of 0-9
• Doesn’t includes commas or spaces.
• Preceded by a + or – sign. + sign is assumed if there isn’t any sign.

Character constants : Any single character enclosed in single quote (‘). Ex :- ‘a’ ,  ’b’ .
Strings : Generally consist of more than one character within double quote (“).
Ex: “comp”, “abcd”.
Difference between String and Character :
Character constant takes 1 byte for storage while string constant takes 2 bytes for storage because in String  a byte is reserved for Null Byte.
Memory representation : 
Character : ‘A’    ==   |A| << stored in one memory cell
String : “A”  ==  |A|\0|  << stored in 2 memory cells with \0 as a NULL byte.
Variables in C++ : These are the tokens that are identified by identified by an identifier and change the value during execution.
Ex : int a=5;
a=a+3;
cout< Here a is a variable. The initial value of a was 5 but it was then changed to 8 by command a=a+3 .