Character Array Declarations

Hi bbac,

The pointer method can not determine the size of the array.  It can determine the size of the string, but not the underlying buffer.

Which one is appropriate in a situation depends a lot on what you want to do with it.


--  Reserve a buffer in the program's variable block and preset it to "aFile.txt".

char filename[20] = "aFile.txt";

--  Reserve a buffer in the program's CONSTANTS block and preset it to "aFile.txt".  Set variable to the address

char *filename = "aFile.txt";


In the first example, filename is an array and behaves just like any other array.  The second example is subtlely different in that filename points to a string in read-only memory.  Try to change the value (perhaps by capitalizing the first character) and the program will abort.


So that's the primary difference.  One puts the buffer in the variables block and initializes it to your value.  The other puts a pointer in the variables block and references memory in the constants block.



Good Luck,
Kent

thanks

hi Kent ,


>>>>>>>>>>>>>" The pointer method can not determine the size of the array.  It can determine the size of the string, but not the underlying buffer. "

               char *ptr  = "hello" ;

 ptr points to a a location in  DS .  ptr is unaware of the size of the string . U can see
                 printf("%d" ,sizeof(ptr));
       
 but when u try o print it
                              printf( "%s" , ptr) , this printf will actually search for  '/0' ,so it will print
the whole text  "hello "


      The allocation in DS for eg:
                      DS: 0x100     h  e l  l  o
                      DS:0x105     '\0'
 is done by the compiler .It purely depends on compiler .  So  i disagree with
           " It can determine the size of the string " 

 

thank you .