Question : General Question: Looping

I am trying to understand looping.  I wrote a simple loop:

L1: for (
L2: $i = 0
L3: $i -le 5
L4: $i++
L5: )
L6: {
L7: write-host "counting to five" $i
L8: }

I put this loop into the Powershell ISE, and put break points on lines 2, 3, 4, and 7.  When I execute the script, the debugger shows the following:

PS C:\WINDOWS\system32\windowspowershell\v1.0> X:\scripts\test\loop.ps1
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:2'
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:3'
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:7'
counting to five 0
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:4'
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:3'
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:7'
counting to five 1
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:4'
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:3'
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:7'
counting to five 2
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:4'
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:3'
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:7'
counting to five 3
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:4'
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:3'
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:7'
counting to five 4
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:4'
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:3'
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:7'
counting to five 5
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:4'
[DBG]>>> Hit Line breakpoint on 'X:\scripts\test\loop.ps1:3'

My question are these - the loop only executes the command on line 2 the first time through the loop.  Why doesn't it execute that line every time through the loop?  After the first pass, the loop then executes line 4.  Why didn't it execute line 4 the first time through the loop (first time through, it skipped from line 3 to line 7).  Finally, why does it execute each subsequent loop in the order of line 4, line 3, and then line 7?

I can create loops, but I would like to understand how the work in the event I need to troubleshoot them.  Can someone maybe provide a link to a good, concise explanation of looping?

Thanks, and Peace.

Answer : General Question: Looping

The definition of a "for" loop for powershell, and many languages, determines which part (or "lines") are executed at what time.

http://www.powershellpro.com/powershell-tutorial-introduction/logic-using-loops/

http://en.wikipedia.org/wiki/For_loop#Three-expression_for_loops