ESP8266 Community Forum

- Thu Jul 14, 2016 2:35 am #50732 You know what? When I read that I remember seeing recently in my SD sketches the following piece of code:

Code: Select allbool SD_exists(String path){
  bool exists = false;
  sd::File test = SD.open(path);
  if(test){
    test.close();
    exists = true;
  }
  return exists;
}


But in the same sketches I do use remove to delete the files

Code: Select allSD.remove((char *)path.c_str());

I guess I'll hook up mu SD and see what will happen

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- Fri Jul 15, 2016 2:37 am #50783 Ah, thanks!

Also, maybe I was calling .remove() with the wrong data type (encapsulated string).

- Sat Jul 16, 2016 8:53 am #50851 Thanks Me-no-dev, it looks like that was it.

This fails with a memory dump:

Code: Select allconst char* myFile = "file.txt";
...
SD.remove(myFile);


But this works as expected, and removes the file:

Code: Select allconst char* myFile = "file.txt";
...
SD.remove((char*)myFile);


eg. I assume by using a type of const char* instead of char*, I need to cast back to a char*

The same with SD.exists() - had to include a cast to char* and then it worked.

My fault (I'm definitely NOT a professional C programmer!) thanks for helping me discover my error.

- Sat Jul 16, 2016 12:16 pm #50861 This behavior is really strange !
I've never seen cases where giving a "const char *" instead of "char *" would cause a crash.
@me-no-dev, anyway, I suggest that SD.remove() and SD.exist() should use "const char *" to be consistent with other SD functions as well as FS functions.