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Return Pointer to local string, destroys the string or not?

Ash J

This forum may not be the best to ask the question, but the answers on the other forums (that i know) were generally with respect to C for desktop pc (where memory management is different from that in embedded) and this forum has knowledgeable embedded people. hence...

I was worried about the following situation:

void function1()
{
  ...     //other variables
  char* ptr = myary;

  ...
  ptr = ReadNandFlash("myfile");
  ...
}

char* ReadNandFlash(char* Filename)
{
  FILE* file;
  char temp_ary[256];

  file = fopen(Filename, "r");

  if(file == NULL)
  {
    return NULL;
  }

  while(!feof(file))
  {
    fread(temp_ary, sizeof(char), 256, file);
  }
  fclose(file);

  return ary;
}

will the 'temp_ary' be destroyed as only the pointer value is returned back to the function1()?

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  • 0 in reply to Ash J

    other way is to pass the 'myary' to 'ReadNandFlash()'
    This will work.

    What you are trying to do may/may-not destroy the array data in the memory. But there is no guarantee of it working always. There may be other piece of code which may change the data (other piece of code can be threads, or may be even an badly written ISR)

Reply
  • 0 in reply to Ash J

    other way is to pass the 'myary' to 'ReadNandFlash()'
    This will work.

    What you are trying to do may/may-not destroy the array data in the memory. But there is no guarantee of it working always. There may be other piece of code which may change the data (other piece of code can be threads, or may be even an badly written ISR)

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