Subj : Re: Local character strings
To   : borland.public.cpp.borlandcpp
From : maeder
Date : Fri Sep 23 2005 07:18 pm

"Ray Sittig" <abuse@support.ahitravel.com> writes:

> #include <stdio.h>
> #include <conio.h>
>
> void main(void);
> void PrintText(int version);
>
> void main()

[Not related to your problem: The return type of main() has to be int
in a C or C++ program.]


> {
> PrintText(2);
> PrintText(1);
> PrintText(2);
> printf( "\nPlease press '1' to continue.\n");
> while (true)
>   {
>   if (getche() == '1')
>     break;
>   }
> }
>
> void PrintText(int version)
> {
> char* MyText[4] =
>  {"2 Line Version: Line 1",
>    "2 Line Version: Line 2"};

As was already posted to in another followup to your post, this
initializes an array of 4 pointers with two non-null and two null
pointers.

Please note that the type of the two character arrays is 'array of 23
char const'. Such an array can only be used to initialize a pointer to
char (non-const!) because of a "deprecated" implicit conversion.


> int number_of_lines_to_print;
> if (version == 1)
>  {
>   number_of_lines_to_print = 1;
>   // once changed - changed for all subsequent calls
>   // therefore MyText not re-initialized
>   MyText[0][0] = '1';

This is the reason why the implicit conversion is deprecated. Your
code modifies a string literal. This means that the program has
undefined behavior. Whatever behavior you see is purely
coincidental. With a little more luck, you'd have seen a crash.

.