-- card: 58255 from stack: in
-- bmap block id: 0
-- flags: 0000
-- background id: 4755
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-- part contents for background part 4
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(mimicking the right-to-left action of the '=' assignment operator).

It is important to distinguish among string constants, character arrays, and character pointers variables, all of which are treated as character pointers.  When a character pointer variable is declared, no space is yet allocated for a character array.  Therefore it is appropriate to use the '=' assignment operator to assign to the pointer variable a pointer to a string, but it is unwise to use strcpy() to assign to the unallocated portion of memory initially pointed to by the pointer variable.  On the other hand when a character array is declared, space is allocated for the array elements.  However, an array name is a constant pointer so it may not be assigned to.  Also, in ANSI C it is illegal to assign a new value to a string constant (although TC still allows this):

    char  *ptr1, ptr2[80], *ptr3;   /* allocate two character pointers and one array */
    ptr1 = "Hello, world!";               /* ok.  ptr1 now points to the constant string */
    *(ptr1+7) = 'x';                           /* illegal!  Attempts to change 'w' in constant string */
    ptr2 = "Hello, world!";               /* illegal!  ptr2 is a pointer constant, not variable */
    strcpy(ptr3,"Hello, world!");   /* incorrect!  Copies string to unallocated memory */



-- part contents for background part 7
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