I have a frustrating problem for which I can't find an answer to.

I have this function:

```
// Append character to the end of a string
void str_AppendChar(char* s, const char* ch)
{
  // +2 because of 2x '\0'
  char* buff = malloc(strlen(s)+strlen(ch)+2);
  memset(buff, 0, sizeof(buff));

  // Copy the whole string in buff
  strcpy(buff, s);

  // Append ch at the end of buff
  int len = strlen(buff);
  strcpy(buff+len, ch);

  // Set end of the string
  *(buff+strlen(buff)-3) = '\0';

  strcpy(s, buff);

  free(buff);
}

```

In which for some reason my program tries to execute free two time at the end.

The code in which I use AppendChar() is:(a bit ugly but bear with me)

```
void it_GatherCmd(cmd_Details* lineptr[], char* cmd)
{
  // Used to count number of rows in lineptr
  int nlines;

  Detailptr p;
  char ch;
  char* word = (char*)malloc(sizeof(char)+256);
  memset(word, 0, sizeof(word));

  nlines = 0;
  while ((ch = *cmd++) != '\n')
  {
      if (ch != ' ' && ch != '\0' )
          str_AppendChar(word, &ch);
      else
      {
          int type = dict_CheckWord(word);

          if (type != -1)
          {
              p = it_CopyInfo(word, type);
              lineptr[nlines++] = p;
          }
          memset(word, 0, sizeof(word));
      }
   }
   //EDIT*
   free(word);
}

```

And my main:

```
int main()
{
   cmd_Details* arrCmd[MAXLINES];
   char* str = "just some string";

   it_GatherCmd(arrCmd, str);

   printf("%s", str);
   return 0;
}

```

AppendChar() was working without problems until I created it\_GetCharCmd() and used it there. I've spent around 3 hours on this and I can't find the problem. Did some searching on the internet but the things I have found didn't exactly relate to my problem.