Video: C# Operators and Expressions (Bulgarian)

Topics covered:

• Operators in C# and Operator Precedence
• Arithmetic Operators
• Logical Operators
• Bitwise Operators
• Comparison Operators
• Assignment Operators
• Other Operators
• Implicit and Explicit Type Conversions
• Expressions

Video (in Bulgarian)

Presentation Content

What is an Operator?

• Operator is an operation performed over data at runtime
  • Takes one or more arguments (operands)
  • Produces a new value
• Operators have precedence
  • Precedence defines which will be evaluated first
• Expressions are sequences of operators and operands that are evaluatedto a singlevalue

Operators in C#

• Operators in C# :
  • Unary – take one operand
  • Binary – take two operands
  • Ternary ( ?: ) – takes three operands
• Except for the assignment operators, all binary operators are left-associative
• The assignment operators and the conditional operator ( ?: ) are right-associative

Categories of Operators in C#

Operators Precedence

Arithmetic Operators

• Arithmetic operators + , - , * are the same as in math
• Division operator / if used on integers returns integer (without rounding) or exception
• Division operator / if used on real numbers returns real number or Infinity or NaN
• Remainderoperator % returns the remainder fromdivision of integers
• The special additionoperator ++ increments avariable

Logical Operators

• Logical operatorstakeboolean operands and return boolean result
• Operator ! turns true to false and false to true
• Behavior of the operators && , || and ^ ( 1 == true , 0 == false ) :

Bitwise Operators

• Bitwise operator ~ turns all 0 to 1 and all 1 to 0
  • Like ! for boolean expressions but bit by bit
• The operators | , & and ^ behave like || , && and ^ for boolean expressions but bit by bit
• The << and >> move the bits (left or right)
• Behavior of the operators | , & and ^ :
• Bitwise operators are used oninteger numbers ( byte , sbyte , int , uint , long , ulong )
• Bitwise operators are applied bit by bit

Comparison Operators

• Comparison operators are used to comparevariables
  • == , < , > , >= , <= , !=
• Comparison operators example:

Assignment Operators

• Assignment operators are used to assign a value to avariable ,
  • = , += , -= , |= ,...
• Assignment operators example:

Other Operators

• String concatenation operator + is used to concatenate strings
• If the second operand is not a string, it isconverted to string automatically
• Member access operator . is used to access object members
• Square brackets [] are used with arrays indexers and attributes
• Parentheses ( ) are used to overridethe default operator precedence
• Class cast operator (type) is used to cast one compatible type to another
• Conditional operator ?: has theform
  • (if b is true thenthe result is x elsethe result is y )
• The new operator is used to create new objects
• The typeof operator returns System.Type object (the reflection of a type)
• The is operator checks if an object is compatible with given type
• Null-coalescing operator ?? isused to define a default value forbothnullable value typesand reference types
  • Itreturns the left-hand operand if it is notnull
    • Otherwiseit returns the rightoperand

Implicit Type Conversion

• Implicit type conversion
  • Automatic conversion of value of onedata typeto value ofanother data type
  • Allowedwhen no loss of data ispossible
    • “Larger” types can implicitly take values of smaller “types”

Explicit Type Conversion

• Explicit type conversion
  • Manual conversion of a value ofone datatype to a value ofanother data type
  • Allowed only explicitlyby (type) operator
  • Required when there is a possibility of loss ofdata or precision

Expressions

• Expressions are sequencesof operators, literals and variables thatareevaluated to somevalue
• Expressions have:
  • Type (integer, real, boolean, ...)
  • Value

Summary

• Wediscussed theoperators in C#:
  • Arithmetic, logical, bitwise, comparison, assignment andothers
  • Bitwise calculations
  • Operator precedence
• We learned when to use implicit and explicit type conversions
• We learned how to use expressions

Resources

• Boolean algebra (logic)
  • http://en.wikipedia.org/wiki/Boolean_algebra_%28logic%29
• Bitwise mask
  • http://en.wikipedia.org/wiki/Mask_%28computing%29
• Bitwise operation
  • http://en.wikipedia.org/wiki/Bitwise_operation
• BitTwiddling Hacks
  • graphics.stanford.edu/~seander/bithacks.html