CODEWITHSUNDEEP
c#stringunsafe
Blorgbeard
Blorgbeard

Reputation: 103467

Copy a C# string to an existing pre-allocated `char*`

I need to copy a C# string into a char*. I have this code, which works, but looks clumsy. Is there a more elegant way to do this?

public unsafe static void GetReply(char* buffer) {
  string reply = "Hello, world"; // or whatever
  // clumsy code:
  var i = buffer;
  foreach (char x in reply.ToCharArray()) {
    *i = x;
    i++;
  }
  *i = '\0';
}

Note: buffer is guaranteed to point to allocated memory of known length. No problems there.

Upvotes: 0

Views: 2707

Answers (2)

Marc Gravell
Marc Gravell

Reputation: 1063015

A simple approach might be:

        for(int i = 0 ; i < reply.Length ; i++) {
            buffer[i] = reply[i];
        }
        buffer[reply.Length] =  '\0';

You could also use fixed(char* chars = reply) {...} and loop over the pointers, but seems overkill.

Upvotes: 3

Ben Voigt
Ben Voigt

Reputation: 283694

You could use Marshal.Copy which is cleaner and likely also faster than the loop.

Upvotes: 5

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