Difference between revisions of "^"
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If it is a typed <syntaxhighlight lang="pascal" enclose="none">pointer</syntaxhighlight>, operations and syntax for that type are valid, e.g. [[Becomes|assignment]] in the following example. | If it is a typed <syntaxhighlight lang="pascal" enclose="none">pointer</syntaxhighlight>, operations and syntax for that type are valid, e.g. [[Becomes|assignment]] in the following example. | ||
− | <syntaxhighlight lang="pascal" line start="21" highlight=" | + | <syntaxhighlight lang="pascal" line start="21" highlight="1-2"> |
// _de-reference_ the pointer, i.e. follow it | // _de-reference_ the pointer, i.e. follow it | ||
start^.payload := 7; | start^.payload := 7; |
Revision as of 23:55, 4 April 2018
│
English (en) │
suomi (fi) │
русский (ru) │
In ASCII the character code decimal 94
(or hexadecimal 5E
) is defined to be ^
(circumflex accent).
For any data type, a pointer
type for that data can be declared using the operator ^
in front of the data type.
1program pointerDemo(input, output, stderr);
2
3type
4 listItem = record
5 payload: integer;
6 // next _points_ _to_ a list item
7 next: ^listItem;
8 end;
9
10var
11 start: ^listItem;
12
13begin
14 new(start);
15 if not assigned(start) then
16 begin
17 writeLn(stderr, 'obtaining memory for start failed');
18 halt(1);
19 end;
A pointer
can be followed by appending a ^
to the identifier.
Instead of having the memory address in your hands, you will look at the memory content at that address.
If it is a typed pointer
, operations and syntax for that type are valid, e.g. assignment in the following example.
21 // _de-reference_ the pointer, i.e. follow it
22 start^.payload := 7;
23
24 dispose(start);
25end.
see also
{$pointerMath}
{$typedAddress}
in conjunction wtih the@
-address-operator
single characters |
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character pairs |
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