dev-cpp-users

Re: [Dev-C++] One other minor problem

[Khalid El-K. <kha...@ho...>]

>I also have one other minor problem.
>
>Though I have looked through over 16 different manuals and tutorials, and 
>have searched over 50 websites I cannot seem to find out the difference 
>between
>
>char* foo;
>char *foo;
>char* *foo;
>
>From my own expirements (purposely generating compiler errors) it >appears 
>to me that the first two are identical.  They both seem to >declare foo to 
>be a variable of type char*.  The second seems to >declare foo a pointer to 
>type char*.  It also appears to me that type >char* is actually a char[] of 
>dynamic length because I can get string >functions to work on it - just 
>like on char[].
>
>I have found no confirmation of any of this though.  I would appreciate 
> >any info anyone has about this.

Your thoughts are right, but the thing that produces compilation error, 
maybe the malloc/realloc/calloc thing associated with them:

//for char**:
char **str_arr;
int num_of_elements = 5;
str_arr = (char**) malloc(num_of_elements*sizeof(char*));

//the for each element of that array you should malloc
str_arr[0] = (char*) malloc(10*sizeof(char);

...

Hope that helps.

>Shane Plesner

Regards,
Khalid Al-Kary


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Re: [Dev-C++] One other minor problem

[Khalid El-K. <kha...@ho...>]

look below :)

>>I also have one other minor problem.
>>
>>Though I have looked through over 16 different manuals and tutorials, and 
>>have searched over 50 websites I cannot seem to find out the difference 
>>between
>>
>>char* foo;
>>char *foo;
>>char* *foo;
>>
>>From my own expirements (purposely generating compiler errors) it >appears 
>>to me that the first two are identical.  They both seem to >declare foo to 
>>be a variable of type char*.  The second seems to >declare foo a pointer 
>>to type char*.  It also appears to me that type >char* is actually a 
>>char[] of dynamic length because I can get string >functions to work on it 
>>- just like on char[].
>>
>>I have found no confirmation of any of this though.  I would appreciate 
>> >any info anyone has about this.
>
>Your thoughts are right, but the thing that produces compilation error, 
>maybe the malloc/realloc/calloc thing associated with them:
>
>//for char**:
>char **str_arr;
>int num_of_elements = 5;
>str_arr = (char**) malloc(num_of_elements*sizeof(char*));
>
>//the for each element of that array you should malloc
>str_arr[0] = (char*) malloc(10*sizeof(char);

//sorry meant:
str_arr[0] = (char*) malloc(10*sizeof(char));

//note the last bracket *shy*

>
>...
>
>Hope that helps.
>
>>Shane Plesner
>
>Regards,
>Khalid Al-Kary
>
>
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RE: [Dev-C++] One other minor problem

[Ioannis V. <iv...@at...>]

> -----Original Message-----
> From: dev...@li... 
> [mailto:dev...@li...] On Behalf 
> Of Khalid El-Kary
> Sent: Sunday, April 13, 2003 6:24 AM
> To: Dev...@li...
> Subject: Re: [Dev-C++] One other minor problem
> 
> >
> >//for char**:
> >char **str_arr;
> >int num_of_elements = 5;
> >str_arr = (char**) malloc(num_of_elements*sizeof(char*));
> >
> >//the for each element of that array you should malloc
> >str_arr[0] = (char*) malloc(10*sizeof(char);
> 
> //sorry meant:
> str_arr[0] = (char*) malloc(10*sizeof(char));
> 
> //note the last bracket *shy*



The castings above are completely unnecessary in C.


E.g.

str_arr = malloc(num_of_elements*sizeof(char*));


In C, a void * is implicitly converted back to any pointer type.




Ioannis Vranos
 
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Re: [Dev-C++] One other minor problem

[Khalid El-K. <kha...@ho...>]

>I was told that I did not need to learn malloc and that other stuff if I 
>was going to use C++.  Is that true?

Yes that's right. I don't know why do I stick to them :-)

>BTW the compiler errors i used were purposely generated like this:
>
>char* foo;
>int bar;
>foo = bar;

foo[0] = 'a'; //for instance
bar = (int) *foo;

foo[1] = 'b'; //also for instance
bar = (int) foo[1] // or bar = *(foo+1);

>that way the compiler would give me something like:
>
>invalid conversion from int to char*.
>
>When I got that I started to wonder because it originally appeared that 
> >foo would be a pointer to a char. not an item of char*.
>

Have a good luck ...

>Shane

Regards,
Khalid AL-Kary


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