[For] A 'For to' which reacts like a 'for downto'

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[For] A 'For to' which reacts like a 'for downto'

Postby Dave_lopez » June 15th, 2004, 8:27 am

Hi everybody,

I got a this extract of code which uses a for:

Code: Select all
For Cpt:=8 to 128 do
  D[CPT] := S.D[CPT];


What's happening ?
Answer:

D[121] := S.D[121];
D[120] := S.D[120];
D[119] := S.D[119];
...
D[2] := S.D[2];
D[1] := S.D[1];

It is driving me crazy ...

Thanx in advance ...
Destiny exists ...
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Postby Kambiz » June 15th, 2004, 9:17 am

The downward for loop is faster than the upward one. Because of that, when direction of the for loop variable doesn't affect the result, the compiler optimizes the code and generates the downward loop.
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