Passing strings to/from DLL

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Hi there,

i'm trying to pass strings from an external DLL to MT4, with no luck. Every time the EA calls the method, MT4 just crashes.

Could someone please point me to a piece of source that exchanges strings with external DLLs or enlighten me by other means?

Here's my non-working code:

c++:

MT4_EXPFUNC void _stdcall doEchos ( std::string& s )

{

s.append("MOOO moo!");

}

MT4 Header:

#import "C:\SDev\...\...\my.dll"

void doEchos ( string& s) ;

#import

MT4 EA:

string ress="";

doEchos(ress);

Any comment?

Thanks,

Armin

 

Three steps:

1- At the top of dll place these lines:

struct MqlStr

{

int len;

char *string;

};[/PHP]

2- In the dll function use something like:

MT4_EXPFUNC long __stdcall test(MqlStr* szTest)

{

}

3- In mq4 use something like:

[PHP]string szTest[];

test(szTest);
 

thanks for pointing this out.

Working in languages with garbage collector for too long made my brain a little soft...

Best wishes,

Armin

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