VBScript Conditions

Bedingte Aussagen d�rfen den Flu� der Durchf�hrung eines Indexes oder des seiner Abschnitte steuern. So verwendest du einige Schl�sselw�rter und verbindest Ausdr�cke mit ihnen. Abh�ngig von dem Resultat der Vergleich Betriebe und anderen �berpr�fenprozesses, kannst du geeignete Schritte nehmen.

Die meisten bedingten Aussagen f�hren Vergleiche und Arbeit auf der Grundlage von Resultat durch. Um dich zu unterst�tzen ausger�stet wenn man solche vergleicht, wird die VBScript Sprache mit speziellen Operatoren die auf nat�rlichen Zahlen, dezimalen Zahlen oder Zeichenketten fungieren k�nnen.

• Equality =
• Inequality <>
• Less Then  <

Du kannst den Flu� deines Indexes mit schlingenaussagen und bedingten Aussagen steuern. Mit bedingten Aussagen kannst du VBScript Code schreiben, der Entscheidungen trifft und T�tigkeiten wiederholt. Die folgenden bedingten Aussagen sind in VBScript vorhanden:

• If...Then...Else statement
• Select Case statement

The If...Then...Else statement is used to evaluate whether a condition is True or False and depending on the result it executes one or more statements. Usually the condition is an expression that uses a comparison operator to compare one value or variable with another value or variable.If...Then...Else statements can be nested up to many levels.

To run only one statement when a condition is True, use the single-line syntax for the If...Then...Else statement. The example given below shows the single-line syntax. Notice that this example neglect the Else keyword.

To run more than one line of code, you must use the multiple-line syntax. This syntax end with the End If statement, as shown in the following example:

You can use an If...Then...Else statement to define two blocks of executable statements: one block to run if the condition is True, the other block to run if the condition is False.

To choose from several alternatives, If...Then...Else statement used. Adding ElseIf clauses expands the functionality of the If...Then...Else statement so you can control program flow based on different possibilities. See following example:

To provide alternative choices you add as many ElseIf clauses as you need. Extensive use of the ElseIf clauses often becomes bulky. A better way to choose between several alternatives is the Select Case statement.

A variation on the If...Then...Else statement allows you to choose from several alternatives. Adding ElseIf clauses expands the functionality of the If...Then...Else statement so you can control program flow based on different possibilities. For example:

With a single test expression a Select Case structure works that is evaluated once.At the top of the structure the result of the expression is compared with the values for each Case in the structure. If there is a match, the block of statements associated with that Case is executed:

Notice that the Select Case structure evaluates an expression once at the top of the structure. In contrast, the If...Then...ElseIf structure can evaluate a different expression for each ElseIf statement. You can replace an If...Then...ElseIf structure with a Select Case structure only if each ElseIf statement evaluates the same expression.