>>I may be way off the mark here because I've never used C18, however,
these examples are either bad or wrong.
>>In C, a "char" is a single character, and normally one byte. A string
is an array of char .
>>Therefore,
>>const char str1 =3D "hello world";
>>is either illegal, or, depending on how the compiler handles it, might
well be the same as saying
>>const char str1 =3D 'h';
>>What you actually want to do is say:-
>>const char[] str1 =3D "hello world";

Yes, just a typo mistake

>>Additionally,
>>
>>const char * str3 =3D "hello world";

That's what I mean to say....

>>is also either illegal, or in some compilers will produce not quite
the effect you're looking for. It would potentially create a char
pointer, which is preconfigured to point to whatever value is
represented by that string. In Win32, pointers are 32 bit, so that would
(in visual c++) create a const char pointer that points to a memory
address of "hell" (0x68656C6C), which is an Access Violation /
Protection fault waiting to happen.

Yes...=20

>>Additionally, remember that a "const char *" is a pointer whose value
(ie what it points to) is fixed, however, you can (normally) write to
the address  pointed to by the pointer. eg:-
>>
>>const char * c =3D 0x70
>>
>>*c =3D 'A' ; // valid-> 0x70 now contains 'A'
>>c =3D &otherchar ; // invalid. c is const.


Well, you are right. I didn't see that, while I actually know it....
Dammm! BUT, I did a test. My compiler says, after compiling that I'm
using 168 bytes of RAM, so I comented a long list of strings (12 screens
for a 20x4 display) defined like:

const char * str3 =3D "hello world";

And nothing changed on the RAM area. Look at the compiler results..:

With all the screens:

Program ROM   $000000 - $000003  $000004 (       4) bytes=20
Program ROM   $000008 - $000013  $00000C (      12) bytes=20
Program ROM   $000018 - $00006F  $000058 (      88) bytes=20
Program ROM   $0000CA - $0005FD  $000534 (    1332) bytes=20
Program ROM   $000D6C - $003B57  $002DEC (   11756) bytes
                                 $003388 (   13192) bytes total Program
ROM

RAM data      $000092 - $0000FF  $00006E (     110) bytes=20
RAM data      $0005CF - $0005FF  $000031 (      49) bytes
                                 $00009F (     159) bytes total RAM data

Near RAM      $000000 - $000007  $000008 (       8) bytes total Near RAM

Near bits     $000040 - $000043  $000004 (       4) bits  total Near
bits   =20

ROM data      $000070 - $0000C8  $000059 (      89) bytes=20
ROM data      $000600 - $000D6A  $00076B (    1899) bytes =20
                                 $0007C4 (    1988) bytes total ROM data


Program statistics: =20

Total ROM used    15180 bytes (46.3%)=20
Total RAM used      168 bytes (10.9%)  =20
Near RAM used        9 bytes (7.0%)=20


Now, without the screens... (12 screens * 20 chars * 4 lines =3D 960
bytes)

Memory Usage Map: =20
Program ROM   $000000 - $000003  $000004 (       4) bytes=20
Program ROM   $00008 -  $000013  $00000C (      12) bytes=20
Program ROM   $000018 - $00006F  $000058 (      88) bytes =20
Program ROM   $0000CA - $0005FD  $000534 (    1332) bytes=20
Program ROM   $000A02 - $0037ED  $002DEC (   11756) bytes
                                  $003388 (   13192) bytes total Program
ROM  =20

RAM data      $000092 - $0000FF  $00006E (     110) bytes=20
RAM data      $0005CF - $0005FF  $000031 (      49) bytes
                                 $00009F (     159) bytes total RAM data


Near RAM      $000000 - $000007  $000008 (       8) bytes total Near RAM

Near bits     $000040 - $000043  $000004 (       4) bits  total Near
bits   =20

ROM data      $000070 - $0000C8  $000059 (      89) bytes=20
ROM data      $000600 - $000A01  $000402 (    1026) bytes =20
                                 $00045B (    1115) bytes total ROM data


Program statistics: =20

Total ROM used    14307 bytes (43.7%)=20
Total RAM used      168 bytes (10.9%)  =20
Near RAM used        9 bytes (7.0%)=20

So, as you can see ther is a difference (873 bytes, don=92t know where =
are
the other 87 bytes to complete the 12 screens...:(

But the important thing is that the difference is on the ROM area and
not in RAM...

>>Hope that ramble helps :)

Yes, it does...

BST RGRDS

Mauricio


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