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Recursive Functions and Variables

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Easy scoping rules:

Scope defines how long the variable persists (exists).

If a variable is defined outside of a function it is "global" in scope. The variable persists for the life of the script.

If you define a variable within a function it is local to that function unless you use the "global" keyword which makes it global in scope. Variables local to a function persist for the life of the function.

This does not pertain to variables defined "static" as this feature is experimental.

kylomas


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@icuurd12b42

Actually For creates a local variable.

This is a good example to illustrate my previous post. If the for loop exists outside of a function then the control variable is "global" in scope, if inside a function then it's scope is local to that function.

kylomas


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- Sir Winston Churchill

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This is a good example to illustrate my previous post. If the for loop exists outside of a function then the control variable is "global" in scope, if inside a function then it's scope is local to that function.

kylomas

After a bit of testing I came up with a demonstration of how this works in AutoIt.

For $i = 1 To 5
        ConsoleWrite("> Outer loop's $I = " & $I & @crlf )
    Test()
Next
ConsoleWrite("> Outer loop's $I (outside the loop) = " & $I & @crlf )
Test2()
Func Test()
    For $I = 1 To 5
        ConsoleWrite("! Inner loop's $I = " & $I & @crlf )
    Next
    ConsoleWrite("' Inner loop's $I (outside the loop)= " & $I & @crlf )
EndFunc
Func Test2()
    ConsoleWrite("> Outer loop's $I (now global) = " & $I & @crlf )
EndFunc

Run this and you'll see that the $I variable outside the function is globally declared, but because you use the same variable in the loop inside the function, THAT one becomes local and doesn't affect the global variable, even though you don't explicitly declare its scope.


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I had the tendency in the past to throw the term 'file scope' around, but I have learnt my lesson since then.


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Thanks. The term was used with my co workers often in my days. It is still a valid term but maybe obsolete? I dont know but good find on wikipedia.

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Every recursive loop can be done with a for/while loop if you think it through.

Recursive things are sometimes hard to grasp and better to be avoided for reasons as: understanding it or safety for your program (you don't want to have 1000 recursive loops)

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