| defined |
(String name [, Object target]) |
reserved |
| defined |
(int index, Object target) |
|
| defined |
(Pointer target) |
|
| |
Looks for an existing definition, either in the current scope or in
target,
and returns
1
if the lookup succeeds and
0
otherwise.
A single argument that is a
String
asks
defined
to look through the current block and all enclosing blocks
for a definition of variable
name.
Two arguments asks whether the object at
index
in
target
is defined, or whether
target
contains a definition of
name.
A single argument that is a
Pointer
but not a
String
(e.g., a
Dictionary
or
Array)
is also allowed and simply asks if the object at
0
in
target
is defined.
In other words,
defined(0, target)
and
defined(target)
are equivalent.
This last style is often used in loops where a pointer's offset,
rather than an integer variable, is being incremented or decremented.
| |
| Example: |
The program,
import yoix.stdio.*;
if (defined("ptr")) {
if (defined("total", ptr))
printf("ptr.total=%d\n", ptr.total);
else printf("ptr.total is not defined\n");
} else printf("ptr is not defined\n");
shows how you can find out if
ptr.total
exists, and if so print its value.
The next program
import yoix.*.*;
Dictionary dict[VM@sizeof + 5] = VM;
for (ptr in dict) {
if (!defined(ptr))
printf("dict[%d] is not defined\n", ptr@offset);
}
prints something like
dict[10] is not defined
dict[12] is not defined
dict[13] is not defined
dict[14] is not defined
dict[15] is not defined
on standard output, which identifies the five unused elements in
dictionary
dict.
Notice how the declaration of
dict
was used to copy
VM
into a new dictionary with exactly five extra elements.
| | |
| Return: |
int
|
|
Yoix is a registered trademark of AT&T Inc.
|
