VBScript

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VBScript

• Session 3

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What We learn Last seasson?

• How to declare arrays.
• Working with one dimensional a multi-dimensional
  arrays.
• Working with Dynamic arrays.
• Arrays utilities (Array,UBound, LBound)

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Subjets for Session 3

• Const Statement.
• Operators.
• Arithmetic.
• Comparision.
• Logical.

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ConstantsConst Statement

• Public Private Const constname expression
• A constant is a meaningful name that takes the
  place of a number or string and never changes.
• VBScript defines a number of intrinsic constants.
  
• You create user-defined constants in VBScript
  using the Const statement.

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ConstantsConst Statement

• You may want to adopt a naming scheme to
  differentiate constants from variables.
• This will prevent you from trying to reassign
  constant values while your script is running.
• For example, you might want to use a "vb" or
  "con" prefix on your constant names, or you might
  name your constants in all capital
  lettersconMaxValue, vbMyValue, MY_VALUE
• Differentiating constants from variables
  eliminates confusion as you develop more complex
  scripts.

Const MyString "This is my string." Const
MyAge 19 Const CutoffDate 6-1-97
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VBScript Operators

• VBScript has a full range of operators, including
  arithmetic operators, comparison operators,
  concatenation operators, and logical operators.
• When several operations occur in an expression,
  each part is evaluated and resolved in a
  predetermined order called operator precedence.
• You can use parentheses to override the order of
  precedence and force some parts of an expression
  to be evaluated before others.
• Operations within parentheses are always
  performed before those outside.

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VBScript Operators

• When expressions contain operators from more than
  one category, arithmetic operators are evaluated
  first, comparison operators are evaluated next,
  and logical operators are evaluated last.
• Comparison operators all have equal precedence
  that is, they are evaluated in the left-to-right
  order in which they appear.
• Arithmetic and logical operators are evaluated in
  the following order of precedence.

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VBScript Operators Arithmetic Operators

• Exponentation operator
• Symbol
• Description Raises a number to the power of an
  exponent.
• Syntax result numberexponent
• Note If either number or exponent is a Null
  expression, result is also Null.
• Substraction operator
• Symbol -
• Description Finds the difference between two
  numbers or indicates the negative value of a
  numeric expression.
• Syntax result number1-number2 -number
• Note If one or both expressions are Null
  expressions, result is Null. If an expression is
  Empty, it is treated as if it were 0.

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VBScript Operators Arithmetic Operators

• Multiplication operator
• Symbol
• Description Multiplies two numbers.
• Syntax result number1number2
• If one or both expressions are Null expressions,
  result is Null. If an expression is Empty, it is
  treated as if it were 0.
• Division operator
• Symbol /
• Description Divides two numbers and returns a
  floating-point result.
• Syntax result number1/number2
• Note If one or both expressions are Null
  expressions, result is Null. If an expression is
  Empty, it is treated as if it were 0.

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VBScript Operators Arithmetic Operators

• Integer Division operator
• Symbol \
• Description Divides two numbers and returns an
  integer result.
• Syntax result number1\number2
• Note Before division is performed, numeric
  expressions are rounded to Byte, Integer, or Long
  subtype expressions.If any expression is Null,
  result is also Null. Any expression that is Empty
  is treated as 0.

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VBScript Operators Arithmetic Operators

• Modulus arithmetic operator
• Symbol Mod
• Description Divides two numbers and returns only
  the remainder.
• Syntax result number1 Mod number2
• Notes The modulus, or remainder, operator
  divides number1 by number2 (rounding
  floating-point numbers to integers) and returns
  only the remainder as result.If any expression
  is Null, result is also Null. Any expression that
  is Empty is treated as 0.

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VBScript Operators Arithmetic Operators

• Addition operator
• Symbol
• Description Sums two numbers.
• Syntax result number1number2
• Note Although you can also use the operator to
  concatenate two character strings, you should use
  the operator for concatenation to eliminate
  ambiguity and provide self-documenting code.

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VBScript Operators Arithmetic Operators

• Concatenation operator
• Symbol
• Description Forces string concatenation of two
  expressions.
• Syntax result expression1 expression2
• Notes Whenever an expression is not a string, it
  is converted to a String subtype. If both
  expressions are Null, result is also Null.
  However, if only one expression is Null, that
  expression is treated as a zero-length string
  ("") when concatenated with the other expression.
  Any expression that is Empty is also treated as
  a zero-length string.

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VBScript Operators Comparision Operators

• Equality and Inequality operators
• Symbol , lt, lt, gt, gt, ltgt
• Description Used to compare expressions.
• Syntax result expression1 comparisonoperator
  expression2
• Note When comparing two expressions, you may not
  be able to easily determine whether the
  expressions are being compared as numbers or as
  strings.
• In operator
• Symbol In
• Description Compares two object reference
  variables.
• Syntax result object1 Is object2
• Note If object1 and object2 both refer to the
  same object, result is True if they do not,
  result is False.

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VBScript Operators Logical Operators

• Logical Conjuction (And) operator
• Symbol Not
• Description Performs logical negation on an
  expression.
• Syntax result Not expression

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VBScript Operators Logical Operators

• Logical Conjuction (And) operator
• Symbol And
• Description Performs a logical conjunction on
  two expressions.
• Syntax result expression1 And expression2

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VBScript Operators Logical Operators

• Logical disjuction (Or) operator
• Symbol Or
• Description Performs a logical disjunction on
  two expressions.
• Syntax result expression1 Or expression2

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VBScript Operators Logical Operators

• Logical Exclusion (Xor) operator
• Symbol Xor
• Description Performs a logical exclusion on two
  expressions.
• Syntax result expression1 Xor expression2