CODEWITHSUNDEEP
c#marshallingstringbuilderunsafefixed
Luca
Luca

Reputation: 11971

Unsafe code and fixed statements with StringBuilder

I was wondering about how passing a String or a StringBuilder to a C function which output a string by parameter. I've found a great answer in

Calling unmanaged function from C#: should I pass StringBuilder or use unsafe code?

But I have a doubt. Anyone can explain to me why the garbage collector doesn't relocate the (managed) StringBuilder instance during imported function execution?

Upvotes: 0

Views: 621

Answers (1)

SoftMemes
SoftMemes

Reputation: 5702

See Default Marshaling for Strings for details on how string and StringBuilder is marshaled when using COM and P/Invoke. It doesn't explicitly say why the usage pattern is safe, but does indicate that using string and StringBuilder for P/Invoke is supported and intended behaviour. I suspect that the marshalling system takes care of pinning the buffer for the duration of the external call, preventing the GC from relocating it.

Upvotes: 1

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