converting from system::String to std::string

Question

To convert from a system::String to an std::string, I use the following code:

IntPtr p = Marshal::StringToHGlobalAnsi(PORT);
string newString = static_cast<char*>(p.ToPointer());
Marshal::FreeHGlobal(p);

However, the place where I got the code uses

IntPtr p = Marshal::StringToHGlobalAnsi(PORT);
char* newString = static_cast<char*>(p.ToPointer());
Marshal::FreeHGlobal(p);

For some reason though, I get garbage in newString if I do the char* version. Anyone know why this would happen?

Thanks.

JaredPar · Accepted Answer · 2012-01-28 02:30:22Z

4

The reason the std::string version works is because it immediately creates a privatecopy of the char* value. This private copy is not affected by the later FreeHGlobal.

The char* version is assigned a pointer to memory which you then free on the very next line. It's invalid the moment the FreeHGlobal command executes.

answered Jan 28, 2012 at 2:30

JaredPar

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Comments

PH Mohmmed Alaa · Accepted Answer · 2021-07-05 11:08:48Z

0

you can Returns a pointer to an array that contains a null-terminated sequence of characters with std::string::c_str then initialize the String^ with the char array

std::string bla = "ConvertMe";
String^ ResultString= gcnew String(bla.c_str());

edited Jul 5, 2021 at 11:08

answered Feb 28, 2021 at 21:43

PH Mohmmed Alaa

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1 Comment

Amit Verma Over a year ago

While this piece of code may provide a solution to the question, it's better to add context as to why/how it works. This can help future users learn and eventually apply that knowledge to their own code. You are also likely to have positive feedback/upvotes from users, when the code is explained.

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