NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/lang/c++-part2/12205

Internet Message Format | 1996-08-05 | 3.0 KB

Path: castle.nando.net!news
From: Caius Martius <[e-mail]>
Newsgroups: gnu.g++.help,comp.lang.c++
Subject: Re: Why not?  c++ Array of strings...
Date: Mon, 18 Mar 1996 16:10:11 -0800
Organization: Nando.net
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Arthur Cinader Jr wrote:
>
> Note Followup
>
> I want a class to a have a member that is an array of
> character strings that are dynamically allocated.  I have written
> a very simple program that shows the eveolution of my thought
> that leads me to beleieve that I should be able to do what I
> am trying, but I get a segmentation fault and core dump when I
> try it.  Why?  I obviously am missing something.  I have kept
> the code as brief as possible (I'm using g++ v2.4):
>
> ***foo.h
> class Foo {
>     public:
>         Foo();      // constructor
>         ~Foo();     // destructor
>     private:
>         char a[10];  // declare and define an array of characters
>         char *b;     // declare a string pointer
>         char *c[10]; // declare an array of ten strings?
> };
>
> ***foo.C
> nclude <iostream.h>
> #include <assert.h>
> #include <string.h>
> #include "foo.h"
>
> // Constructor -- all the action is here --
> Foo::Foo()
> {
>         // populate the character array
>         a[0] = 'a';
>         a[1] = 'r';
>         a[2] = 't';
>         a[3] = 'h';
>         a[4] = 'u';
>         a[5] = 'r';
>
>         // print the character array
>         cout << "output from array of char: ";
>         for(int i = 0 ; i < 6 ; i++)
>                 cout << a[i];
>
>         cout << endl;
>
>         // populate the string
>         b = new char[7];                // allocate space
>         assert( b != 0);                // make sure space was allocated
>         strcpy(b, "arthur");
>
>         // print the string
>         cout << "output from *char: " << b;
>
>         cout << endl;
>
>         // So far so good.  This is where it all falls apart
>         // populate array of strings
>         c[0] = new char[10];    // allocate space
>         assert(c[0] != 0);      // make sure space was allocated
>         strcpy(c[0], "arthur");
>         c[1] = new char[10];
>         assert(c[1] != 0);
>         strcpy(c[1], "cinader");
>         c[2] = new char[10];
>         assert(c[2] != 0);
>         strcpy(c[2], "jr.");
>
>         // output array of strings
>         for (i = 0 ; i < 3 ; i--)  // *** This should be unary increment. ++ ***
>                 cout << c[i] << " ";
>
>         cout << endl;
>
> }
>
> Foo::~Foo() {
>         // clean up the mess
>         delete [] b;
>         for(int i = 0; i < 3; i --) // *** This should be unary increment. ++ ***
>                 delete [] c[i];
> }
>
> **** foo.driver.C
> #include "foo.h"
>
> main()
> {
>         Foo f;
>
>         return 0;
> }