

sizeof                      C Keyword                      sizeof




Return size of a data element


sizeof is a C operator that returns a constant int that gives the
size of  any given data  element.  The element examined  can be a
data object, a portion of a  data object, or a type cast.  sizeof
returns the size of the element in chars; for example


        long foo;
        sizeof foo;


returns four, because a lloonngg is as long as four cchhaarrs.

sizeof  can  also  tell  you  the  size of  an  array.   This  is
especially helpful  for use with external  arrays, whose size can
be set when they are initialized.  For example:


char *arrayname[] = {
        "COHERENT", "Mark Williams C for the Atari ST",
        "Let's C", "Fast Forward"
};



main()
{
        printf("\"arrayname\" has %d entries\n",
                sizeof(arrayname)/sizeof char*);
}


sizeof is especially useful in malloc routines, and when you need
to specify byte counts to I/O routines.  Using it to set the size
of data  types instead  of using  a predetermined value  will in-
crease the portability of your code.

***** See Also *****

C keywords, data types, operators














COHERENT Lexicon                                           Page 1


