NetNews Usenet Archive 1992 #20/NN_1992_20.iso/spool/comp/lang/cplus/13370

Text File | 1992-09-08 | 2.0 KB | 72 lines

Newsgroups: comp.lang.c++
Path: sparky!uunet!news.mentorg.com!sdl!adk
From: [e-mail] (Ajay Kamdar)
Subject: Re: can I 'delete' without a 'new'?
Message-ID: <[e-mail]>
Organization: Mentor Graphics Corp. - IC Group
References: <[e-mail]>
Date: Mon, 7 Sep 1992 18:20:55 GMT
Lines: 61

In article <[e-mail]> [e-mail] (Peter Uchytil) writes:
>I can't seem to find any references which indicate whether I can do this
>or not, so I'm appealing to the net.wisdom.  Here's what I've got:
>
>class foo {
>  char *String;
>public:
>  foo();
>  foo( char * );
>  ~foo();
>  void set( char * );
>};
>
>foo:foo() { };
>
>foo:foo( char *inString ) {
>  String = new char[strlen( inString )];
>  strcpy( String, inString );
>}
>
>void foo:set( char *inString ) {
>  String = new char[strlen( inString )];
>  strcpy( String, inString );
>}
>
    You have a severe bug in the above code. When you new a character array
    to hold a copy of the inString, you want to allocate space for ONE MORE
    than the length of the string (to hold the terminating '\0'). i.e.,
    String = new char[strlen(inString) + 1+;
    strcpy(String, inString);


>foo:~foo() {
>  delete [] String;
>}
>
>The question is what will happen if I create a foo with the empty constructor
>and never call 'set'?  Since 'new' has never been called, what will 'delete'
>try to delete?  Looks like a real good way to frazzle the system.  Yes?  No?
>

    Yes, a real good way to frazzle the system. What you want to do is
    to set String to 0 in the default constructor as follows:

    foo::foo() : String(0) {}

>
>But then does 'set' first have to do a 'delete' before doing another 'new'?
>I would assume it does.
>

     Yes, you need to do a delete before doing a new in set().


- Ajay

--
I speak for none but myself.

Ajay Kamdar                               Email : [e-mail]
Mentor Graphics, IC Group (Warren, NJ)    Phone : [phone]