Visual Basic and Visual FoxPro loops
VBA
Do While, Do Until, Exit Do, Loop
While, Wend
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VFP
Do While, Loop, Exit, EndDo
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Visual Basic Syntax Notes
Visual Basic has four related types of loop with similar syntax. These run
While or Until the test
condition is true and allow the test condition to be at the beginning or the end of the
loop. A couple of examples:
x = 1
Do While x < 100
x = x * 2
? x
Loop
or
x = 1
Do
x = x * 2
? x
Loop Until x >= 100
Use the Loop keyword to skip the rest of the code in the
body of the loop and return immediately to the top. Use the
Exit Do commands to break out of the loop and
execute the statement following the end of the structure.
Visual Basic also has the separate While...Wend structure
which has been retained for backwards compatibility with GW-BASIC. This structure has the
test at the start of the loop.
Visual FoxPro Syntax Notes
FoxPro just has the loop with While
at the beginning so it is not possible to initialise the test condition inside the body
of the loop. The test variable must exist and have a value before the loop is entered:
x = 1
Do While x < 100
x = x * 2
? x
EndDo
Use the Loop keyword to skip the rest of the code in the
loop and return immediately to the test in the While
statement. Use the Exit command to break out of the loop and
execute the statement following EndDo.
FoxPro does have another specialist type of loop command. The
scan
command is specifically designed for processing data in tables.
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