[fpc-pascal] DLL call works on FPC 2.6.4 but not with D7
Jonas Maebe
jonas.maebe at elis.ugent.be
Tue Jul 1 20:58:33 CEST 2014
On 01/07/14 19:42, Paul Breneman wrote:
> I'm doing the same thing in FPC and D7:
> StringLen := 14;
> MyReturnStr := 'test1234567890';
> Status := ps5000aGetUnitInfo( ps5000a_handle, @MyReturnStr[ 0],
> StringLen, requiredSize, RInfo);
It wrong in both FPC and D7 (and it will also crash on all platforms in
the next version of FPC; in the current version, it will only crash on
OS X). You are assigning a string constant to a pchar, and then telling
the DLL to overwrite it.
In current release versions of FPC (where it doesn't crash), that will
result in the data of that string constant getting overwritten. This
means that if you assign 'test1234567890' somewhere else to a string,
that string will actually get the value with which this string was
overwritten the last time.
Use getmem to allocate writeable memory.
Jonas
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