Campbell Scientific CR9000X Measurement and Control System - Manual (Page 339)

Section 9. Program Control Instructions
Changing the value of counter while inside a loop can make the
program more difficult to read and debug. TIP
You can nest For...Next loops by placing one For...Next loop within another.
Give each loop a unique variable name as its counter. The following
construction is correct:
For J = 5 To 1 Step -1 'Loop 5 times backwards.
For I = 1 To 12 'Loop 12 times.
. . . . 'Run some code.
Next I
. . . 'Run some code.
Next J
. . . . 'Run some code.
If you omit the variable in a Next statement, the value of Step
increment is added to the variable associated with the most
recent For statement. If a Next statement is encountered before
its corresponding For statement, an error occurs. NOTE
Nested For...Next Statement Bubble Sort Example
If Flag(3) Then 'Perform Bubble Sort based on
Flag(3)
For K = 1 To 29
For I = 30 To (K) Step -1
If PlaceDist(I) > PlaceDist(K) Then
DistD = PlaceDist(K) 'Dummies to hold Place K values
TractorD = TractorNum(K)
PlaceDist(K) = PlaceDist(I) 'Assign New Standing
TractorNum(K) = TractorNum(I)
PlaceDist(I) = DistD
TractorNum(I) = TractorD
EndIf
Next I
Next K
Flag(3) = False
EndIf
This next example fills odd elements of X up to 40 * Y with odd numbers.
For I = 1 To 40 * Y Step 2
X( I ) = I
Next I
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