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Clear Structures
Posted: Tue Aug 08, 2006 1:57 pm
by jqn
Code updated for 5.20+ (better to use ClearStructure(), especially when the structure contains strings, array, list or map which have been allocated internally by PureBasic)
Hi,
A little piece of code:
Code: Select all
Structure mystruc
field1.s
field2.l
field3.q
field4.f
field5.d
EndStructure
Macro showit
PrintN(Str(Len(mystruc\field1))+" : "+mystruc\field1)
PrintN(Str(mystruc\field2))
PrintN(Str(mystruc\field3))
PrintN(StrF(mystruc\field4))
PrintN(StrD(mystruc\field5))
PrintN("size "+Str(SizeOf(mystruc)))
PrintN("")
EndMacro
Global mystruc.mystruc
OpenConsole()
mystruc\field1 = "STRING DATA FIELD 1"
mystruc\field2 = 2006
mystruc\field3 = 123456789
mystruc\field4 = 987654321
mystruc\field5 = -987654321
PrintN("BEFORE")
showit
base = @mystruc
For n=0 To SizeOf(mystruc)-1
PokeB(base+n,0)
Next
PrintN("AFTER")
showit
Input()
End
Posted: Tue Aug 08, 2006 2:56 pm
by Guimauve
Little bit more simple.
Regards
Guimauve
Code: Select all
Structure mystruc
field1.s
field2.l
field3.q
field4.f
field5.d
EndStructure
Macro showit
PrintN(Str(Len(mystruc\field1))+" : "+mystruc\field1)
PrintN(Str(mystruc\field2))
PrintN(StrQ(mystruc\field3))
PrintN(StrF(mystruc\field4))
PrintN(StrD(mystruc\field5))
PrintN("size "+Str(SizeOf(mystruc)))
PrintN("")
EndMacro
Global mystruc.mystruc
OpenConsole()
mystruc\field1 = "STRING DATA FIELD 1"
mystruc\field2 = 2006
mystruc\field3 = 123456789
mystruc\field4 = 987654321
mystruc\field5 = -987654321
PrintN("BEFORE")
showit
; base = @mystruc
; For n=0 To SizeOf(mystruc)-1
; PokeB(base+n,0)
; Next
RtlZeroMemory_(mystruc, SizeOf(mystruc))
PrintN("AFTER")
showit
Input()
End
Posted: Tue Aug 08, 2006 4:55 pm
by Deeem2031
And the string..?
Posted: Tue Aug 08, 2006 9:37 pm
by netmaestro
Quite right, the pointer to it is gone but the string is still there. This should zero the string as well:
Code: Select all
Structure mystruc
field1.s
field2.l
field3.q
field4.f
field5.d
EndStructure
Macro showit
PrintN(Str(Len(mystruc\field1))+" : "+mystruc\field1)
PrintN(Str(mystruc\field2))
PrintN(StrQ(mystruc\field3))
PrintN(StrF(mystruc\field4))
PrintN(StrD(mystruc\field5))
PrintN("size "+Str(SizeOf(mystruc)))
PrintN("")
EndMacro
Global mystruc.mystruc
OpenConsole()
mystruc\field1 = "STRING DATA FIELD 1"
mystruc\field2 = 2006
mystruc\field3 = 123456789
mystruc\field4 = 987654321
mystruc\field5 = -987654321
PrintN("BEFORE")
showit
RtlZeroMemory_(@mystruc\field1, Len(mystruc\field1))
RtlZeroMemory_(@mystruc, SizeOf(mystruc))
PrintN("AFTER")
showit
Input()
End
Posted: Wed Aug 09, 2006 1:49 pm
by remi_meier
I think that's not what he meant
Posted: Wed Aug 09, 2006 5:09 pm
by netmaestro
Sorry - what did he mean then?
Posted: Thu Aug 10, 2006 1:57 pm
by Deeem2031
You should free the memory of the string. If you zero the string the memory is still allocated.
Posted: Thu Aug 10, 2006 3:44 pm
by Psychophanta
Deeem2031 wrote:You should free the memory of the string. If you zero the string the memory is still allocated.
The topic said "clear", but not to free the structure.
And BTW, about this thread: is this a trick or a sort of a "Hello world!" example?
Posted: Thu Aug 10, 2006 4:08 pm
by helpy
BUT! If you clear the string pointer in a structure, you produce a memory leak!
Test this:
Code: Select all
Macro Pause
MessageRequester("PAUSE", "Check memory usage in task manager")
EndMacro
Structure test
l.l
StructureUnion
s.s
ps.l
EndStructureUnion
EndStructure
#TestLoop = 1024 * 1024
Pause
For i = 1 To #TestLoop
a.test\s = Space(32)
a\ps = #Null
Next i
Pause
Posted: Thu Aug 10, 2006 4:33 pm
by Psychophanta
Of course, the "tip" or "trick" is very ugly, unelegant and bad done.
