Pointer Operators

The relational operators <, >, <=, and >= can take operands of type PChar and PWideChar (see Relational operators). The following operators also take pointers as operands. For more information about pointers, see Pointers and pointer types.

Character-pointer operators

Operator Operation Operand Types Result Type Example

+

pointer addition character pointer, integercharacter pointer P + I

- pointer subtraction character pointer, integercharacter pointer, integerP - Q

A

pointer dereferencepointer

base type of pointer PA

=

equality pointer

Boolean P = Q

<>

inequality pointer

Boolean P <> Q

The a operator dereferences a pointer. Its operand can be a pointer of any type except the generic Pointer, which must be typecast before dereferencing.

p = q is True just in case p and q point to the same address; otherwise, p <> q is True.

You can use the + and - operators to increment and decrement the offset of a character pointer. You can also use - to calculate the difference between the offsets of two character pointers. The following rules apply.

  • If I is an integer and p is a character pointer, then p + I adds I to the address given by p; that is, it returns a pointer to the address I characters after p. (The expression I + p is equivalent to p + I.) p - I subtracts I from the address given by p; that is, it returns a pointer to the address I characters before p. This is true for PChar pointers; for PWideChar pointers p + I adds sizeOf (WideChar) to P.
  • If p and q are both character pointers, then p - q computes the difference between the address given by p (the higher address) and the address given by q (the lower address); that is, it returns an integer denoting the number of characters between p and q. p + q is not defined.
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