Migrate function C++ with pointers to C#

I have a function in C++ that returns pointer values​​:

fPosFirst( int &aId, char *aNname, char *aDirectory );

My syntax in c# is:

fPosFirst(ref int aId,  String aNname,  String aDirectory);

the function retur开发者_开发问答ns the id but not the string parameters that anyone knows?

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If you want the parameters to be used for returning values then mark them as ref or out.

E.g.

fPosFirst(ref int aId,  out string aNname,  out string aDirectory);

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Assuming that the native function does not "return pointers" but writes characters to the memory locations specified by aNname and aDirectory, you should be able to pass a StringBuilder with a proper capacity to the native function:

void fPosFirst(ref int aId, StringBuilder aNname, StringBuilder aDirectory);

Usage:

var aId = 0;
var aNname = new StringBuilder(260);
var aDirectory = new StringBuilder(260);

fPosFirst(ref aId, aNname, aDirectory);

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You need to make the string parameters ref or out if you want to assign to them within the method and have those values available outside the method.

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You need to use out keyword before parameters names (example). But actually this is not good practice in C#