What is an Expression and What are the types of Expressions? (original) (raw)

Last Updated : 2 Aug, 2019

Expression: An expression is a combination of operators, constants and variables. An expression may consist of one or more operands, and zero or more operators to produce a value. Example:

a+b c s-1/7*f . . etc

Types of Expressions:

Expressions may be of the following types:

• Constant expressions: Constant Expressions consists of only constant values. A constant value is one that doesn't change.Examples:
  5, 10 + 5 / 6.0, 'x’
• Integral expressions: Integral Expressions are those which produce integer results after implementing all the automatic and explicit type conversions.Examples:
  x, x * y, x + int( 5.0)
  where x and y are integer variables.
• Floating expressions: Float Expressions are which produce floating point results after implementing all the automatic and explicit type conversions.Examples:
  x + y, 10.75
  where x and y are floating point variables.
• Relational expressions: Relational Expressions yield results of type bool which takes a value true or false. 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.Examples:
  x <= y, x + y > 2
• Logical expressions: Logical Expressions combine two or more relational expressions and produces bool type results. Examples:
  x > y && x == 10, x == 10 || y == 5
• Pointer expressions: Pointer Expressions produce address values. Examples:
  &x, ptr, ptr++
  where x is a variable and ptr is a pointer.
• Bitwise expressions: Bitwise Expressions are used to manipulate data at bit level. They are basically used for testing or shifting bits. Examples:
  x << 3
  shifts three bit position to left
  y >> 1
  shifts one bit position to right. Shift operators are often used for multiplication and division by powers of two.

Note: An expression may also use combinations of the above expressions. Such expressions are known as compound expressions.