Komputer for Alle 2002 #3

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Extensible Markup Language | 2001-09-07 | 6.5 KB | 76 lines

<?xml version="1.0" encoding="utf-8"?> <html><head><title>Do...Loop Statement [Runtime]</title><meta name="filename" content="text/sbasic/common/03090201"/><help:css-file-link xmlns:help="http://openoffice.org/2000/help"/><style type="text/css"> p.P1{ } span.T1{ font-weight:bold;} </style></head><body> <help:to-be-embedded Eid="doloop" xmlns:help="http://openoffice.org/2000/help"><a name="doloop"/> <help:link Id="66463">Do...Loop Statement [Runtime]</help:link> Repeats the statements between the Do and the Loop statement while the condition is True or until the condition becomes True. </help:to-be-embedded> Syntax <help:key-word value="Do" tag="kw66463_1" xmlns:help="http://openoffice.org/2000/help"/>Do [{<help:key-word value="While" tag="kw66463_4" xmlns:help="http://openoffice.org/2000/help"/>While | <help:key-word value="Until" tag="kw66463_3" xmlns:help="http://openoffice.org/2000/help"/>Until} condition = True] statement block [Exit Do] statement block <help:key-word value="Loop" tag="kw66463_2" xmlns:help="http://openoffice.org/2000/help"/>Loop or Do statement block [Exit Do] statement block Loop [{While | Until} condition = True] Param./Element Condition: A comparison, numeric or string expression that evaluates either True or False. Statement block: Statements to be repeated while or until the condition is True. The Do...Loop statement is used to execute a loop as long as (or until) a certain condition is True. The condition for exiting the loop must be entered following either the Do or the Loop statement. The following examples are valid combinations: Syntax Do While condition = True ...statement block Loop The program tests the condition. If the condition is False, the program continues directly after the Loop statement. If the condition is True, the loop is activated, and the program jumps back to the Do statement. If the condition is still True, the loop will be repeated, otherwise the program execution continues with the statement following the Loop statement. To summarize: The loop will be repeated as long as the condition is true. Do Until condition = True ...statement block Loop The program tests the condition. If the condition is True, the program continues directly after the Loop statement. If the condition is not True, the loop is activated, and the program jumps back to the Do statement. If the condition is still not True, the loop will be repeated, otherwise the program execution continues with the statement following the Loop statement. To summarize: The loop will only be repeated, if the condition is False at first, and then until the condition becomes true. Do ...statement block Loop While condition = True The program initiates the loop immediately. At the Loop statement, the condition is tested. If the condition is True, the program repeats the loop starting from the Do statement. Only when the condition following Loop becomes False,the program will end the loop. To summarize: The statements within the loop will be executed once in each case, and as long as the condition is true. Do ...statement block Loop Until condition = True The program initiates the loop immediately. At the Loop statement, the condition is tested. If the condition is not True, the program repeats the loop starting from the Do statement. Only when the condition following Loop becomes True, the program will end the loop. To summarize: The statements within the loop will be executed once in each case, and until the condition becomes true. The main difference between the above mentioned statements is that in the first two cases, the loop is initiated dependent on the condition. In the last two examples, the statements between Do und Loop are executed once at least. The Exit Do statement ends the loop unconditionally. This statement is placed anywhere within a Do...Loop statement. You can define an exit condition using the If...Then structure as follows: Do... statements If condition = True Then Exit Do statements Loop... Example Sub ExampleDoLoop Dim sFile As String Dim sPath As String sPath = "c:\" sFile = Dir$( sPath ,22) If sFile <> "" Then Do MsgBox sFile sFile = Dir$ Loop Until sFile = "" End If End Sub </body></html>