How many extra bytes are in the string?

[AZJIO]

I have heard that when creating a string, a little more bytes are allocated than necessary, so when adding a pair of CRLF characters to a string, there is no memory overallocation (ReAllocateMemory) and it works quickly. I'm wondering how many bytes are allocated more than required. How many characters can I add to a string without causing memory overload.

[skywalk]

Ouch, that is not guaranteed behavior.
You must assume your string byte length is accurate and not use "behind the scenes" padding.

[AZJIO]

and not use "behind the scenes" padding.

This will be the standard method

Code: Select all

strind + #CRLF$ + #TAB$

But I want to make sure that +#TAB$ doesn't cause memory over-allocation.

I want to know in which case I can use the normal method and in which case I have to use the CopyMemoryString() function.

[mk-soft]

It is requested as much memory as one needs and goes coherently.

You can also forcibly release the string memory

Start without debugger as console and watch memory

Code: Select all

Define i.i, s.s

mb = 1024*1024*16

If OpenConsole()
  i + 1
  PrintN("" + i + ": no string")
  Input()
  i + 1
  s = Space(mb)
  PrintN("" + i + ": 16mb unicode string")
  Input()
  i + 1
  s + Space(mb)
  PrintN("" + i + ": plus 16mb unicode string")
  Input()
  i + 1
  PrintN("" + i + ": release string")
  s = #Null$
  Input()
  
EndIf

[SMaag]

I struggled with this at my early Assembler tests with Strings. At the beginning I did not understand what are the values after the end of the String.

The allocation is 4 Byte aligned at x86 and 8 Byte aligend at x64. So number of charcters * SizeOf(Charcter) + CHR(0) + FillBytesForMemoryAling
So you can write without problems until the end of the aligned size. At x64 and Charsiez=2 this are maximal 3 characters more than you String.

[mk-soft]

PureBasic decides internally how much memory is reserved behind the string ...

Code: Select all

Define a$

For i = 1 To 100
 a$ + "x"
 Debug "pString = " + @a$
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