Undefined values: Difference between revisions
Content added Content deleted
(→{{header|Python}}: Modified comments to stress creation/deletion. There is no 'undefined' value to give.) |
m (→[[Undefined values#ALGOL 68]]: rename some variables) |
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Note: Some implementations (eg [[ALGOL 68C]]) also have a procedure named ''undefined'' that is called to indicated that the behaviour at a particular point in a program is unexpected, undefined, or non-standard. |
Note: Some implementations (eg [[ALGOL 68C]]) also have a procedure named ''undefined'' that is called to indicated that the behaviour at a particular point in a program is unexpected, undefined, or non-standard. |
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<lang algol68>MODE |
<lang algol68>MODE R = REF REAL; |
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R r := NIL; |
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MODE U = UNION(COMPL, VOID); |
MODE U = UNION(COMPL, VOID); |
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U u := EMPTY; |
U u := EMPTY; |
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IF |
IF r IS R(NIL) THEN |
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print((" |
print(("r IS NIL", new line)) |
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ELSE |
ELSE |
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print((" |
print(("r ISNT NIL", new line)) |
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FI; |
FI; |
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(VOID):print(("u is EMPTY", new line)) |
(VOID):print(("u is EMPTY", new line)) |
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OUT print(("u isnt EMPTY", new line)) |
OUT print(("u isnt EMPTY", new line)) |
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ESAC |
ESAC |
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</lang> |
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Output: |
Output: |
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<pre> |
<pre> |
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r IS NIL |
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u is EMPTY |
u is EMPTY |
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</pre> |
</pre> |
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