CBSE Class 12 Computer Science Programming In C++ Concepts

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.

♦ C++ is the successor of C language.

♦ It is a case sensitive language.

 Character Set- Set of characters which are recognized by c++compiler i.e Digits (0-9), Alphabets (A-Z & a-z) and special characters + - * , . “ ‘ < > = { ( ] ) space etc i.e 256 ASCII characters.

 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:

   i) First letter of identifier is always alphabet.

   ii) Reserve word cannot be taken as identifier name.

   iii) 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(!).

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

i) 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.

ii) 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;

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.

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