dev-cpp-users

[Dev-C++] pointer help

[Noorez K. <coo...@ho...>]

Need some help understanding pointers.

I can understand this

int main()
{
   char charArray[10];
   char* pArray = charArray;
   for(int i =0; i <10; i++)
   {
     *pArray ='\0';
      pArray++;
   }
}

I don't inderstand this. It came from a book I am reading

char* pszMonth;
pszMonth = "January";

this is just a bit of code. But I don't see how this can be. First how can 
you make the assignment without the * and how can you put a string in a char 
pointer. A char like that should only hold one character.

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Re: [Dev-C++] pointer help

[Nicolas R. <ni...@bo...>]

> I don't inderstand this. It came from a book I am reading
>
> char* pszMonth;
> pszMonth = "January";
>
> how can you put a string in a char pointer. A char like that should 
> only hold one character


Your book is using C string conventions. C has no special data type for 
character strings; instead they are stored as arrays of characters. 
(Indeed, arrays and pointers have lots in common -- hint: the char 
pointer is pointing to the 1st char of the array). C provides special 
support for character arrays that do not extend to other kinds of 
arrays. For example, C provides ways to print them (in printf and other 
output statements) and to read them (in scanf and other input 
statements). C also provides a number of library routines that compute 
the lengths of strings, append two strings, and the like. It also 
provides special syntax to "assign" strings to char pointers, which is 
where that strange assignment comes to life.

C++ provides higher level abstractions, such as a proper 'string' class 
and a 'vector' container class.

I'd advise you to

a) google for:  c string pointer array char
     (e.g. see http://www.sepsis.za.net/programming_c07.html)

b) google for:  c++ string class
     (e.g. see http://www.bgsu.edu/departments/compsci/docs/string.html)

c) google for:  c++ faq "arrays are evil"
     (e.g. see 
http://www.parashift.com/c++-faq-lite/containers-and-templates.html)

Good luck!
N.

Re: [Dev-C++] pointer help

[Per W. <pw...@ia...>]

A character pointer is a pointer to a character. A string is a sequence of
characters. Because of that, it is possible for a character pointer to
point at the first character of the string.

See more below.

/Per W

On Thu, 27 May 2004, Noorez Kassam wrote:

> Need some help understanding pointers.
>
> I can understand this
>
> int main()
> {
>    char charArray[10];
>    char* pArray = charArray;
>    for(int i =0; i <10; i++)
>    {
>      *pArray ='\0';
>       pArray++;
>    }
> }
>
> I don't inderstand this. It came from a book I am reading
>
> char* pszMonth;
> pszMonth = "January";

Will point to the 'J' character of January. A printout using pszMonth will
then print out all characters until the terminating zero that ends the
string "January". The psz prefix means Pointer to Zero-terminated String.

The assign is of course without a '*' since the assign is of one pointer
(address of string "January" to another pointer pszMonth. Had a star been
used on pszMonth, you might have written:

char ch;
char* pszChar = &ch; // Make pointer point at some available space.
*pszChar = 'J';      // Assign a character to *pszChar position, i.e. ch.

ch will now be 'J', since pszChar pointed to ch - thereby making the above
assignment the same as ch = 'J'.

>
> this is just a bit of code. But I don't see how this can be. First how can
> you make the assignment without the * and how can you put a string in a char
> pointer. A char like that should only hold one character.
>
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