CH 1:REVIEW OF C++

REVIEW OF C++
CHAPTER 1

UNIT 1 : PROGRAMMING IN C++

Introduction to C++

• C++ programming language developed by AT&T Bell Laboratories in  1979 by Bjarne Stroustrup. C++ is fully based on Object Oriented Technology i.e. C++ is ultimate paradigm for the modeling of information.
  
  
  Tokens- Smallest individual unit. Following are the tokens
• Keyword-Reserve word having special meaning the language and can’t be used as
  identifier.
• Identifiers-Names given to any variable, function, class, union etc. Naming convention (rule) for writing identifier is as under:
  1. First letter of identifier is always alphabet.
  2. Reserve word cannot be taken as identifier name.
  3. No special character in the name of identifier except under score sign ‘_’.
• Literals-Value of specific data type assign to a variable or constant. Four type of Literals: i) Integer Literal   i.e int x =10 ii) Floating point Literal  i.e float x=123.45
        iii)Character Literal  i.e char x= ‘a’, enclosed in single quotes and single character only. iv) String Literal  i.e cout<< “Welcome” , anything enclosed in double quotes
• Operator – performs some action on data o Arithmetic(+,-,*,/,%) o Assignment  operator (=) o Increment / Decrement  (++, --) o Relational/comparison (<,>,<=,>=,==,!=). o Logical(AND(&&),OR(||),NOT(!).
  Conditional (? :)
• Punctuation – used as separators in c++ e.g. [  {  (  )  }  ] ,  ;  #  =  : etc
  Precedence of operators:

++(post increment),--(post decrement)	Highest Low
++(pre increment),--(pre decrement),sizeof !(not),-(unary),+unary plus)
*(multiply), / (divide), %(modulus)
+(add),-(subtract)
<(less than),<=(less than or  equal),>(greater than), >=(greater than or equal to)
==(equal),!=(not equal)
&& (logical AND)
||(logical OR)
?:(conditional expression)
=(simple assignment) and other assignment operators(arithmetic assignment operator)
, Comma operator

Data type- A specifier to create memory block of some specific size and type. C++offers two types of data types:

1. Fundamental type : Which are not composed any other data type i.e. int, char, float and void
2. Derived data type : Which are made up of fundamental data type i.e array, function, class, union etc
   Data type conversion- Conversion of one data type into another data type. Two type of conversion i.e

1. Implicit Conversion – It is automatically taken care by complier in the case of lower range to higher range e.g. int x, char c=’A’ then x=c is valid i.e character value  in c is automatically converted to integer.
2. Explicit Conversion- It is user-defined that forces an expression to be of specific type.
   e.g. double x1,x2 and int res then  res=int(x1+x2)
   Variable- Memory block of certain size where value can be stored and changed during program execution. e.g. int x, float y, float amount, char c;
   Constant- Memory block where value can be stored once but can’t changed later on during program execution.e.g. const int pi =3.14;
   cout – It is an object of ostream_withassign class defined in iostream.h header file and used to display value on monitor.
   cin – It is an object of istream_withassign class defined in iostream.h header file and used to read  value from keyboard for specific variable.
   comment- Used for better understanding of program statements and escaped by the compiler to compile . e.g. – single line (//) and multi- line(/*….*/)
   Cascading – Repeatedly use of input or output operators( “>>” or “<<”) in one statement with cin or cout.

			Control Structure:
Sequence control statement(if )	conditional statement (if else)	Multiple Choice Statement If –else-if		Switch Statement (Alternate for ifelse- if) works for only exact match		loop control statement (while ,do… while, for)
Syntax	Syntax	Syntax		Syntax		Syntax
if(expressio n) { statements; }	If(expressio n) { statements; } else { statements; }	If (expression) { statements } else if(expression) { statement } else { statement }		switch(int / char variable) { case literal1: [statements break;] case literal2: [statements, break;] default:statements; } Break            is compulsory statement with every case because if it is not included then the controls executes next case statement until next break encountered or end of swtich reached. Default is optional, it        gets           executed when no match is found		while(expression) { statements; } Entry control loop works for true condition. do { statements; } while(expression); Exit Control           Loop execute at least once if the condition is false at beginning. for loop for(expression1;expressio n2;expression3) { statement;} Entry            control           loop works for true condition and preferred for fixed no.of times.

Note: any non-zero value of an expression is treated as true and exactly 0 (i.e. all bits contain 0) is treated as false.

Nested loop -loop within loop.

exit()- defined in process.h and used to terminate the program depending upon certain condition. break- exit from the current  loop depending upon certain condition.

continue- to skip the remaining statements of the current loop and passes control to the next loop control statement.

goto- control is unconditionally  transferred to the location of local label specified by <identifier>. For example A1:

cout<<”test”;
goto A1;

Some Standard C++ libraries
	Header	Nome Purpose
	iostream.h	Defines stream classes for input/output streams
	stdio.h	Standard input and output
	ctype.h	Character tests
	string.h	String operations
	math.h	Mathematical functions such as sin() and cos()
	stdlib.h	Utility functions such as rand()

Some functions

• isalpha(c)-check whether the argument is alphabetic or not.
• islower(c)- check whether the argument is lowecase or not.
• isupper(c) - check whether the argument is upercase or not.
• isdigit(c)- check whether the argument is digit or not.
• isalnum(c)- check whether the argument is alphanumeric or not.
• tolower()-converts argument in lowercase if its argument is a letter.
• toupper(c)- converts argument in uppercase if its argument is a letter.
• strcat()- concatenates two string.
• strcmp-compare two string.
• pow(x,y)-return x raised to power y.
• sqrt(x)-return square root of x.
• random(num)-return a random number between 0 and (num-1)
• randomize- initializes the random number generator with a random value.
  Array- Collection of element of same type that are referred by a common name.

One Dimensional array

• An array is a continuous memory location holding similar type of data in single row or single column. Declaration in c++ is as under:
  const int size =20; int a[size] or   int a[20]. The elements of array accessed with the help of an index. For example : for(i=0;i<20;i++) cout<<a[i];
• String (Array of characters) –Defined in c++ as one dimensional array of characters as
  char s[80]= “Object oriented programming”;

Two dimensional array

 A two diamensional array is a continuous memory location holding similar type of data arranged in row and column format (like a matrix structure).

Declaration – int a[3][4], means ‘a’ is an array of integers are arranged in 3 rows & 4 columns.

Function -Name given to group of statements that does some specific task and may return a value. Function can be invoked(called) any no. of time and anywhere in the program.

Function prototypes-Function declaration that specifies the function name, return type and parameter list of the function.

syntax: return_type function_name(type var1,type var2,….,type varn );

Actual Parameters

Variables associated with function name during function call statement.

Formal Parameters

Variables which contains copy of actual parameters inside the function definition.

Local variables

 Declared inside the function only and its scope and lifetime is function only and hence accessible only inside function.

Global variables

 Declared outside the function and its scope and lifetime is whole program and hence accessible to all function in the program from point declaration.

Example :

#include <iostream.h> int a=20; // global void main()

{ int b=10; // local cout<<a<<b;

}

Passing value to function-

• Passing by value- In this method separate memory created for formal arguments and if any changes done on formal variables , it will not affect the actual variables.So actual variables are preserved in this case
• Passing by address/reference- In this method no separate memory created for formal variables i.e formal variables share the same location of actual variables and hence any change on formal variables automatically reflected back to actual variables.
  Example :
  void sample( int a, int &b)
  { a=a+100;
  b=b+200; cout<<a<<b;
  }
  void main() {
  int a=50, b=40;
  cout<<a<<b;   // output 50  40 sample(a,b)   // output 150  240 cout<<a<<b; // output   50  240
  }

Function overloading

• Processing of two or more functions having same name but different list of parameters.
   Structure-Collection of logically related different data types (Primitive and Derived) referenced under one name.
                 e.g.    struct employee                                                                                                           
  { int empno; char name[30]; char design[20]; char department[20];
  }
              Declaration:     employee e;
  Input /Output : cin>>e.empno; // members are accessed using dot(.) operator. cout<<e.empno;
  Nested structure

• A Structure definition within another structure.
• A structure containing object of another structure.
              e.g.      struct address
                          {          int houseno;
  char city[20];       char area[20];
  long int pincode;}
                 struct employee
  { int  empno;
  char name[30];
  char design[20];
   char department[20];
  address ad;  // nested structure }
  
  
              Declaration:     employee e;
  Input /Output : cin>>e.ad.houseno; // members are accessed using dot(.) operator. cout<<e.ad.houseno;
  typedef
  Used to define new data type name.
  e.g. typedef char Str80[80];  Str80   str;
  #define Directives
   Use to define a constant number or macro or to replace an instruction.

source: CBSE key notes