Source code to Val procedure

Posted on 2004-04-15
Last Modified: 2010-05-18

According to Delphi 7 help, the Val procedure is in the system unit. I can't find it there. I want to know if it always returns zero when Code is non zero.

My question is, where is the source code for Val?


Question by:wipnav
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LVL 11

Expert Comment

ID: 10833418
You dont actually get the source code. The function/procedure prototypes are stored in the units like system. The function/procedure is a object file so you cannot view the source.

Well that is how C works, so, I guess that delphi will do the same.
LVL 12

Expert Comment

ID: 10833592

   Project / Options / Compiler / Debuggins

   set there "Use Debug DCU" and when you execute your code Step Into the procedure ...
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Expert Comment

ID: 10833619

   Your system unit is in folder C:\Program Files\Borland\Delphi5\lib, unit system.dcu.

   Obviously the code you have in Source/RTL/Sys is not the unit compiled into this DCU. So use Step Into after you turn "Use Debug DCU". I think this should help ...
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LVL 22

Expert Comment

by:Ferruccio Accalai
ID: 10833735
The Val source code isn't available because it's built into the compiler

The System.pas header comment say:
             { Predefined constants, types, procedures, }
             { and functions (such as True, Integer, or }
             { Writeln) do not have actual declarations.}
             { Instead they are built into the compiler }
             { and are treated as if they were declared }
             { at the beginning of the System unit.     }
LVL 22

Accepted Solution

Ferruccio Accalai earned 50 total points
ID: 10833902
BTW: -->I want to know if it always returns zero when Code is non zero.

Not exactly. It depends on the type of the returned var.
Delphi syntax:

procedure Val(S: String; var V; var Code: Integer);

if S is '1.2' and V is integer, code will be 1 and V the integer part of S that is 1 in this case....

So not every time that Code is non zero return 0 for V also...

Hope is clear...
LVL 22

Expert Comment

by:Ferruccio Accalai
ID: 10833918
--> if S is '1.2' and V is integer, code will be 1
should be
if S is '1.2' and V is integer, code will be 2
sorry for the typo

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