Sunday, 14 August 2016

Expressions and their types

                                          EXPRESSION AND THEIR TYPES

An expression is a combination of operators, constants and variables arranged as per the rules of the language.It may also include functions calls which return values.An expression may consist of one or more operands , and zero or more operators to produce a value. expressions may be of the following seven types.


  • Constant expressions 
  • Integral expressions 
  • Float expressions
  • pointer expressions
  • Relational expressions
  • Logical expressions
  • Bitwise expressions
An expression may also use combination of the above expression . Such expression are known as compound expressions.


CONSTANT EXPRESSIONS

CONSTANT expressions consist of only constant values. EXAMPLE:

15

20+5/2.0

'X'


INTEGRAL EXPRESSIONS 

integral expressions are those which produce integer results after implementing all the automatic and explicit type conversions . EXAMPLE :

m

m*n-5

m*'X'

5+ int(2.0)
where m and n are integer variables.

FLOAT EXPRESSIONS

Float expressions are those which,after all conversions, produce floating-point results.
EXAMPLE:

x+y

x*y /10

5 + float(10)

10.75

where x and y are floating-point variables.

POINTER EXPRESSIONS 

Pointer expressions produce address values.example:

&m

ptr

ptr +1

"xyz"
where x is a variable and ptr is a pointer.

RELATIONAL EXPRESSIONS 

Relational expressions yield results of type bool which takes a value true or false. Examples:

x<=y

a+b == c+d

m+n>100

When arithmetic expressions are used on either side of a relational operator,they will be evaluated first and then the results compared . Relational expressions are also known as BOOLEAN EXPRESSIONS .

LOGICAL EXPRESSIONS

Logical expressions combine two or more relational expressions and produces bool type results. Examples:

a>b &&x==10

x==10|| y==5

BITWISE EXPRESSIONS

Bitwise expressions are used to manipulate data at bit level.They are basically used for testing or shifting bits .Examples:

x<<3 // shift three bit position to left
y>>1 // shift one bit position to right

Shift operators are often used for multiplication and division by power of two.

ANSI c++ has introduced what are termed as operator keyword that can be used as alternative representation for operator symbols . 

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