I ran a little test of passing array by value and reference. Normally, variables passed by value can be used like local variables in the called function or procedure. They can be modified within the called code without changing the value in the caller's code. Seems right.
But this doesn't seem to work the same for arrays. The compiler lets me modify the array in the called code but does NOT actually do the modification! No error or warnings are generated.
PROGRAM p6;
{$H-}
USES
sysutils;
TYPE
pass_test = Array[1..4] of Integer;
VAR
ta : pass_test;
i : Integer;
//===================
PROCEDURE pbv(x : pass_test);
VAR
i : Integer;
BEGIN
for i := 1 to 4 DO
x[i] := 2 * i;
Writeln('End of pbv: ', ta[1], ' ', ta[2], ' ', ta[3], ' ', ta[4]);
END;
//====================================
PROCEDURE pbr(var x : pass_test);
VAR
i : Integer;
BEGIN
for i := 1 to 4 DO
x[i] := 2 * i;
Writeln('End of pbr: ', ta[1], ' ', ta[2], ' ', ta[3], ' ', ta[4]);
END;
//===== Main ====
BEGIN
Writeln('Start p_test');
for i := 1 to 4 DO
ta[i] := i;
Writeln('Initial array: ', ta[1], ' ', ta[2], ' ', ta[3], ' ', ta[4]);
pbv(ta);
Writeln('After pbv: ', ta[1], ' ', ta[2], ' ', ta[3], ' ', ta[4]);
pbr(ta);
Writeln('After pbr: ', ta[1], ' ', ta[2], ' ', ta[3], ' ', ta[4]);
END.
/code]
Output is:
-----------Start p_test
Initial array: 1 2 3 4
End of pbv: 1 2 3 4
After pbv: 1 2 3 4
End of pbr: 2 4 6 8
After pbr: 2 4 6 8
I expected End of pbv to be 2 4 6 8
Any suggies?
Thanx ... Charlie
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