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delphidelphi-10-seattle

Delphi GetTickCount is not a valid integer

I am trying to set a unique id using GetTickCount

I am doing the following 

var
UniqueID : DWORD;
LastUniqueID : DWORD;
uniqueString : string;
begin

UniqueID := GetTickCount;
LastUniqueID := GetTickCount + 1000;

uniqueString  := intTostr(LastUniqueID);//or UniqueID 

end;

I got invalid integer value on uniqueString := intTostr(LastUniqueID);

Project project1.exe raised exception class EConvertError with message ''2312357250' is not a valid integer value'.

what am I doing wrong ?

Solution

  • Unfortunately, you have shown code that does not match the error message that you report. Your actual code calls StrToInt rather than IntToStr. I know this because that error message is produced by calls to StrToInt rather than IntToStr.

    Your code looks more like this:

    UniqueID := StrToInt('2312357250');

    Note that StrToInt returns a signed 32 bit integer type. Valid values are in the range -2,147,483,648 to 2,147,483,647. Your value is outside the valid range for Integer, hence the error.

    If you want a simple way to side step all these range issues, then use Int64 instead of DWORD or Integer, and call StrToInt64.

    Furthermore, these lines are troublesome:

    UniqueID := GetTickCount;
LastUniqueID := GetTickCount + 1000;

    You make two distinct calls to GetTickCount. These two calls may yield different values. Indeed, if GetTickCount rolls over, then the second call may return a value that is less than the first one.

    Yet more troubles surround GetTickCount + 1000. If GetTickCount returns a value close to the upper limit, then you will encounter integer overflow, which may have results that you don't expect. Use GetTickCount64 to avoid that pitfall.

    However, I remain to be convinced that the system tick count can is a good way to generate a unique ID. Depending on your requirements, this may well be a poor solution to your problem, whatever it is. On the face of it, your code appears to preclude requesting a unique ID less than a second later than the previous time you requested one. Of course, without knowing your requirements it is hard to recommend an alternative.