B VBScript03

VBScript Session 3

What We learn Last seasson? How to declare arrays. Working with one dimensional a multidimensional arrays. Working with Dynamic arrays. Arrays utilities (Array,UBound, LBound)

Subjets for Session 3

Const Statement. Operators. Arithmetic. Comparision. Logical.

Constants Const Statement

[Public | Private 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.

Constants Const 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 letters: conMaxValue, 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#

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.

Dani Vainstein

6

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 l eft-to-right order in which they appear. Arithmetic and logical operators are evaluated in the following order of precedence.

VBScript Operators Arithmetic Operators Exponentation operator Symbol : ^ Description:: Raises a number to the power of an exponent. Description Syntax:: result = number^ Syntax number^exponent Note:: If either number  or exponent  is a Null expression, result  is also Null Note Null..

Substraction operator Symbol : Description: Finds the difference between two numbers or indicates the Description: negative value of a numeric expression. Syntax:: result = number1-number2 : -number Syntax Note: If one or both expressions are Null expressions, result  is Null Note: Null.. If an expression is Empty Empty,, it is treated as if it were 0.

VBScript Operators Arithmetic Operators Multiplication operator Symbol : * Description:: Multiplies two numbers. Description Syntax:: result = number1*number2 Syntax If one or both expressions are Null expressions, result  is Null Null.. If an expression is Empty, Empty, it is treated as if it were 0.

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

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

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

VBScript Operators Arithmetic Operators Addition operator Symbol : + Description:: Sums two numbers. Description Syntax:: result = number1+number2 Syntax Note: Although you can also use the + operator to concatenate Note: two character strings, you should use the &  & operator operator for concatenation to eliminate ambiguity and provide self-documenting code.

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

VBScript Operators Comparision Operators Equality and Inequality operators Symbol : =, =, Description:: Used to compare expressions. Description Syntax:: result = expression1 comparisonoperator expression2 Syntax Note: When comparing two expressions, you may not be able to easily Note: determine whether the expressions are being compared as numbers or as strings.

In operator Symbol : In Description:: Compares two object reference variables. Description Syntax:: result = object1 Is object2 Syntax Note: If object1 and object2 both refer to the same object, result  is True Note: True;; if they do not, result  is False False..

VBScript Operators Logical Operators Logical Conjuction (And) operator Symbol

: Not

Description: Syntax:

Performs logical negation on an expression.

result = Not expression

If Ex Expr pres essi sion on is

The Th e re resu sult lt is

True

False

False

True

Null

Null

VBScript Operators Logical Operators Logical Conjuction (And) operator Symbol : And Description: Performs a logical conjunction on two expressions. Syntax: result = expression1 And expression2 If expression1 is

And expression2 is

The

result  is

True

True

True

True

False

False

True

Null

Null

False

True

False

False

False

False

False

Null

False

Null

True

Null

Null

False

False

Null

Null

Null

VBScript Operators Logical Operators Logical disjuction (Or) operator Symbol : Or Description:: Performs a logical disjunction on two expressions. Description Syntax:: result = expression1 Or expression2 Syntax If expression1 is

And expression2 is

The

result  is

True

True

True

True

False

True

True

Null

True

False

True

True

False

False

False

False

Null

Null

Null

True

True

Null

False

Null

Null

Null

Null

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

If expression1 is True

And expression2 is

The

result  is

True

False

True

False

True

False

True

True

False

False

False