INTRODUCTION TO C++

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INTRODUCTION TO C++

  C++ IS A GENERAL PURPOSE PROGRAMMING LANGUAGE CREATED BY BJARNE STROUSTRUP IN 1980S AT BELL LABS. C++ IS A STATICALLY TYPED, COMPILED, GENERAL PURPOSE, CASE SENSITIVE, FREE FORM PROGRAMMING LANGUAGE THAT SUPPORT PROCEDURAL, OBJECT ORIENTED, AND GENERIC PROGRAMMING.
C++ IS REGARDED AS A MIDDLE LEVEL LANGUAGE, AS IT COMPRISES A COMBINATION OF BOTH HIGH LEVEL AND LOW LEVEL LANGUAGE FEATURES. C++ SUPPORTS OBJECT ORIENTED PROGRAMMING, INCLUDING THE FOUR PILLARS OF OBJECT ORIENTED PROGRAMMING.


  1.  ENCAPSULATION
  2.  DATA HIDING
  3.  INHERITANCE
  4.  POLYMORPHISM


A SIMPLE C++ PROGRAM

# INCLUDE < IOSTREAM.H >
# INCLUDE < CONIO.H >
VOID MAIN( )
{
COUT<< " SIMPLE C++ PROGRAM WITHOUT USING CLASS ";
GETCH( );
}
  • LINES BEGINNING WITH A HASH SIGN ( # ) ARE DIRECTIVES READ AND INTERPRETED BY WHAT IS KNOWN AS THE PREPROCESSOR. THEY ARE SPECIAL LINES INTERPRETED BEFORE THE COMPILATION OF THE PROGRAM ITSELF BEGINS. IN THIS CASE, THE DIRECTIVE # INCLUDE< IOSTREAM.H > , INSTRUCTS THE PREPROCESSOR TO INCLUDE A SECTION OF STANDARD C++ CODE, KNOWNS AS HEADER IOSTREAM THAT ALLOWS TO PERFORM STANDARD INPUT AND OUTPUT OPERATIONS, SUCH AS WRITING THE OUTPUT OF THIS PROGRAM ON THE SCREEN.
  • THE FUNCTION NAMED MAIN IS A SPECIAL FUNCTION IN ALL C++ PROGRAMS, IT IS THE FUNCTION CALLED WHEN THE PROGRAM IS RUN. THE EXECUTION OF ALL C++ PROGRAMS BEGIN WITH THE MAIN FUNCTION, REGARDLESS OF WHERE THE FUNCTION IS ACTUALLY LOCATED WITH IN THE CODE.
  • THE OPEN BRACE { INDICATES THE BEGINNING OF MAIN FUNCTION DEFINITION,  AND THE CLOSE BRACE } INDICATES ITS END.
  • THE STATEMENT  COUT<< " SIMPLE C++ PROGRAM WITHOUT CLASS "; CAUSES THE STRING IN QUOTATION MARK TO BE DISPLAYED ON THE SCREEN. THE IDENTIFIER COUT DENOTES AN OBJECT. IT POINTS TO THE STANDARD OUTPUT DEVICE NAMELY THE CONSOLE MONITOR. THE OPERATOR << IS CALLED INSERTION OPERATOR. IT DIRECTS THE STRING ON ITS RIGHT TO THE OBJECT ON ITS LEFT.
  • THE PROGRAM END WITH THIS STATEMENT GETCH( );

CHARACTER SET

    THE ALPHABETS, WHICH ARE THE FUNDAMENTAL UNITS OF A LANGUAGE ARE COLLECTIVELY KNOWN AS CHARACTER SET. CHARACTER SET OF C++ IS,

  • LETTERS  : A TO Z, a to z ( ALPHABETS )
  • DIGITS  :   0 TO 9  ( NUMERALS )
  • SPECIAL CHARACTERS :  + - * / ^ % ( ) { } [ ] = ! < > . , " & ETC

 TOKENS

    IT IS THE SMALLEST INDIVIDUAL UNIT IN A PROGRAM. C++ HAS FIVE TYPES OF TOKENS AS LISTED.

  1. KEYWORDS
  2. IDENTIFIERS
  3. LITERALS
  4. PUNCTUATORS
  5. OPERATORS

KEYWORDS

     RESERVED WORDS WHICH GIVES SPECIAL MEANING TO THE LANGUAGE COMPILER ARE CALLED KEYWORD.



IDENTIFIERS

     IDENTIFIERS ARE NAMES GIVEN TO A VARIABLE, FUNCTION, CLASS.
RULES FOR NAMING IDENTIFIERS :
  • VARIABLE NAMES CAN START WITH ANY LETTER OF THE ALPHABET OR, A DIGIT, OR AN UNDERSCORE.
  • UPPERCASE AND LOWERCASE ARE DISTINCT.
  • C++ KEYWORDS CANNOT BE USED AS IDENTIFIER.

LITERALS

 IT REFER TO A FIXED VALUES THAT CANNOT CHANGED DURING EXECUTION. ALSO KNOWN AS CONSTANT.



1. INTEGER CONSTANT


THE TOKENS CONSTITUTED BY ONLY THE DIGITS ARE CALLED INTEGER CONSTANT.

EXAMPLE : 123, -2860, +52


1. DECIMAL CONSTANT


 AN INTEGER CONSTANT CONSISTING OF A SEQUENCE OF DIGITS IS TAKEN TO BE DECIMAL INTEGER.

 EXAMPLE : 123, -2860


2. OCTAL CONSTANT

A SEQUENCE OF DIGITS STARTING WITH 0 IS TAKEN TO BE OCTAL.

 EXAMPLE : -042, 077

3. HEXADECIMAL CONSTANT


 0 TO 9 AND A TO F
EXAMPLE : 0X12A, OX976B



2. FLOATING POINT CONSTANT
 NUMBER CONTAINING FRACTIONAL PART IS FLOATING POINT CONSTANT.

 EXAMPLE :  6.2, 4.23


3. CHARACTER CONSTANT

 CHARACTER ENCLOSED IN A PAIR OF DOUBLE QUOTES.

EXAMPLE : "CPP", "NAME"


 ESCAPE SEQUENCE


PUNCTUATORS

   PUNCTUATORS ARE THE TOKENS OR SYMBOLS THAT ARE USED TO SEPARATE THE TOKENS USED IN THE PROGRAM AND HENCE THEY ARE ALSO KNOWN AS SEPARATORS.


[ ]  ---> BRACKETS - ARRAY DECLARATION

{ } --->  BRACES    - BLOCK OF CODE

( ) --->  PARENTHESES - FUNCTION CALL, FUNCTION DECLARATION

;   --->  SEMI COLON

.   --->  PERIOD  -  DE REFERENCING
 

OPERATORS

   OPERATORS ARE THE TOKENS THAT TRIGGERS SOME KIND OF OPERATIONS ON THE DATA. THERE ARE 5 TYPES OF OPERATORS IN C++.

  1. ARITHMETIC OPERATORS
  2. RELATIONAL OPERATORS
  3. LOGICAL OPERATORS
  4. CONDITIONAL OPERATORS
  5. BITWISE OPERATORS

ARITHMETIC OPERATORS

   THESE OPERATORS PERFORM THE BASIC ARITHMETIC OPERATIONS SUCH AS ADDITION, SUBTRACTION, MULTIPLICATION, AND DIVISION.




RELATIONAL OPERATORS

   THESE OPERATORS PERFORM COMPARISON OPERATION BETWEEN QUANTITIES.


LOGICAL OPERATORS

  THEY PERFORM LOGICAL OPERATIONS THAT REQUIRE BOOLEAN VALUE AS OPERANDS AND RETURN BOOLEAN VALUES.


CONDITIONAL OPERATORS

   IT IS THE TERNARY OPERATOR OF C++ AND IT REQUIRES THREE OPERANDS.


SYNTAX :  IF  EXP1 ? EXP 2 : EXP 3;

EXAMPLE : IF ( MARK > 40 ) 'P' : 'F';

BITWISE OPERATORS

   THESE ARE THE OPERATORS FOR MANIPULATION OF DATA AT BIT LEVEL.


 

DATA TYPES

   DATA TYPE INDICATE THE NATURE AND RANGE OF VALUES A VARIABLE CAN HOLD.


 


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