Replacing a character in a char array

[UserLoser.]

I have a character array, and what I want to do is get rid of " and , in the array... I can't get it working correctly.  What I have, which doesn't work but I want something similar to it, but working..

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   for (i = 0; i <= strlen(text); i++)
   {
      if ((text[i] == '"') || (text[i] == ','))
      {
          strcpy(text, text + i + 1);
      }
   }


If I ran test through that, it'd result in test - working
If I ran "test through that, it'd result in test - working
If I ran ,test through that, it'd result in test - working
If I ran test" through that, it'd result in test" - not working
If I ran ,test" through that, it'd result in test" - not working

So basically, if there were either a , or a " or both, on both sides of the character array, how can I remove those?

[Zakath]

Just offhand, I would say that you might have problems because you're changing the value against which your iterator is tested. When you call strcpy, you change the length of the string. Then it calls strlen, which potentially could return a new, smaller number. I would change the loop like this:

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for ( i = 0, j = strlen( text ); i <= j; i++ )

See if that helps at all.

[Adron]

Code Select Expand


  for (i = 0; i < strlen(text); i++)
  {
     if ((text[i] == '"') || (text[i] == ','))
     {
        memmove(text + i, text + i + 1, strlen(text+i+1));
        i--;
     }
  }


Some small changes: Don't increase i after a match because you moved the text forward instead. Only move the text one position. The behaviour of strcpy is undefined when the strings overlap. No need to process the string terminator.

[Maddox]

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  for (i = 0; i < strlen(text); i++)
  {
     if ((text[i] == '"') || (text[i] == ','))
     {
        memmove(text + i, text + i + 1, strlen(text+i+1));
        i--;
     }
  }


Some small changes: Don't increase i after a match because you moved the text forward instead. Only move the text one position. The behaviour of strcpy is undefined when the strings overlap. No need to process the string terminator.

This won't copy over the null terminator. You can correct this by changing strlen(text+i+1) to strlen(text+i+1)+1.

Additionally, this should work as well:

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char *p = text;
while(*p)
{
     if ((*p == '"') || (*p == ','))
        memmove(p, p + 1, strlen(p + 1) + 1);
     else
        p++;
}


[Adron]

Additionally, this should work as well:

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char *p = text;
while(*p)
{
     if ((*p == '"') || (*p == ','))
        memmove(p, p + 1, strlen(p + 1) + 1);
     else
        p++;
}


As would this:

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for(char *p = text, *q = text; *p == '"' || *p == ',' || (*q++ = *p); p++);
 

[UserLoser.]

Thanks everyone!

I havn't tested these (been busy with other more important problems), but I'm assuming they work due to the fact of the people who replied