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John Kouraklis

Difference between Pred and -1

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I am looking at some older code and I see the author uses the following statement:


for i:=0 to Pred(WhateverList.count) do


instead of the usual one:


for i:=0 to WhateverList.count - 1 do


Does it make any real difference or it's just a personal preference?



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In that code statement it does not matter if Pred() or attached -1 will be used. Both do same but Pred() can do more than give back decremented number.


Those types are supported:

Characters, Non-floating number types, Enumeration types and Pointers 



Character := Pred( Char( 'X' ) ); = W



It might be possible that on mass operations a -1 is faster than using Pred().

Not tested by myself but possible.

(not for above example, when used inside loops)

Edited by KodeZwerg

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