#include <stdlib.h> /* required for malloc */
   ...
   char *mymsg;
   ...
   mymsg = malloc (sizeof (char) * <some number of elements>);
   if (mymsg)
   {
       /* do something interesting here */
   }

If the buffer is static in size (that is, you know how long it needs to be), use

   char mymsg[<some number of elements>]

Note you can do something like

   char *mymsg = "Hello";
   char yourmsg[] = "Goodbye";

In both cases, the array size is computed from the initializer string.  The
difference is that mymsg may or may not be writable, depending on the
implementation, while yourmsg will be writable.

--
John Bode
"Paranoia is just reality on a finer scale" -- Strange Days

To email me directly, remove the 'nospam.' from my address.

In addition to the above if you can get your hands on a copy of The C
Programming Language by Kernighan and Richie read pages 104 thru 107.
The FAQ, in Section 6.2, references these pages  in K&R and I find it
really helps to read both!

Good luck,

Kevin

Please help newbie to c.

It seems that there are two way to declare strings in c

char *mymsg;
or
char mymsg[ ];

when should I declare one way over the other?  If I declare the first
way, I do I reinitialize it to null?

Thanks in advance

Section 6 of the FAQ (Frequently Asked Questions list) for
comp.lang.c has a good discussion on the difference between
pointers and arrays in C.  It also has a lot of other useful
information on common C programming issues.  You can get the FAQ
at www.eskimo.com/~scs/C-faq/top.html.

If you still have questions about defining strings after you
read the FAQ, post them here.

Happy Programming

Jack

: Please help newbie to c.

: It seems that there are two way to declare strings in c

There is no 'string' type in C.

: char *mymsg;

That is a pointer to char,not a string.

: or
: char mymsg[ ];

That would be an array of char, you are missing the size, however.
It would be OK if you declared it extern and defined it elsewhere.

: when should I declare one way over the other?  If I declare the first
: way, I do I reinitialize it to null?

Well it depends on what you want.  With a pointer you can allocate
memory dynamically, with an array the size is static.

gabor.
--
    If you want your program to be readable, consider supplying the argument.
        -- Larry Wall in the perl man page

<snip>

Remember that the compiler creates a separate null-terminated string for
"Hello" and "Goodbye". As you said earlier, char *mymsg is a pointer to
a char. Therefore, the result of char *mymsg = "Hello" is that mymsg
contains a pointer to the letter 'H'. The string is not copied. The
result of char yourmsg[] = "Goodbye" is that yourmsg contains a copy of
"Goodbye". You now have two copies of the string.

Have fun,
Zev Griner

Now you can use malloc() to allocate some storage to give the pointer
something to point at:
mymsg = malloc( 81 );  /* Allocates 81 bytes of storage for a 'string'
*/
You can now input data into the 'string'.

Another possibility:

char *msg_p;
char msg[] = "Hello out there.";

msg_p = msg;
I have now set the pointer to point to the start of the string "Hello
out there."

This is a common mistake:

char *stra;
char *strb = "Hello World.";

strcpy( stra, strb ); /* This is an error. */

The problem is that you have not allocated any storage for stra.
strcpy() will copy strb to whereever stra (uninitialized) just happens
to point to.  On most modern systems you will get some kind of
protection fault when you try to write to memory that your application
does not 'own' (has no read/write rights to).  Once in a blue moon the
garbage in stra will equate to an address inside your data space and you
will trash some of your data.  On DOS systems you can do all kinds of
damage.  Problems, I might add, that might not show up until you run
some other program.

Read the C-FAQ
www.eskimo.com/~scs/C-faq/top.html.

Look at the `Net resources available:
C Programming `Net Resources
http://www.cit.ac.nz/smac/cprogram/cstart.htm
http://www.angelfire.com/sc/electron/
http://www.cm.cf.ac.uk/Dave/C/CE.html
http://www.lysator.liu.se/c/
http://www-isis.ecs.soton.ac.uk/computing/c/notes/tao.html
http://www.cast.msstate.edu/~billy/c-prog.html

And get yourself a good book (The C Programing Langauge, by Kernigan and

--

Education is a companion which no misfortune can depress,
no crime can destroy, and no enemy can alienate...
at home a friend, abroad an introduction,
in solitude a solace, and in society and ornament.
                                Joseph Addison.
************************************************

You can't use void main() I have a patent on it!

************************************************

*    Remove the _JUNK_ when replying to me.    *
************************************************

: > or
: > char mymsg[ ];

: This style does in fact create an empty string.  Declaring:
: char mymsg[81];
: allocates as much storage for character data as the previous method.

The rest of your explanations was cool, however, the above is a syntax
error.  You cannot declare an 'empty' string.  mymsg needs to be
either :
defined elsewhere and then declared extern in your current file
or must include the size of the array.

gabor.
--
    Does the same as the system call of that name.
    If you don't know what it does, don't worry about it.
        -- Larry Wall in the perl man page regarding chroot(2)