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31 lines
1.2 KiB
Markdown
31 lines
1.2 KiB
Markdown
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The [LOCK](LOCK) statement restricts access to parts of a file by other programs or processes.
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## Syntax
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> [LOCK](LOCK) [#]fileNumber%
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> [LOCK](LOCK) [#]fileNumber%, record&
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> [LOCK](LOCK) [#]fileNumber%, [firstRecord&] TO lastRecord&
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## Description
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* fileNumber% is the file number of the file to lock.
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* In the first syntax, the entire file is locked.
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* In the second syntax, record& is the record number of the file to lock.
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* In the third syntax, the records or bytes in the range [firstRecord&,lastRecord&] are locked. If firstRecord& is omitted, it is assumed to be one (the first record or byte).
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* For files opened in [BINARY](BINARY) mode, each record corresponds to a single byte.
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* [LOCK](LOCK) and [UNLOCK](UNLOCK) statements are always used in pairs and each statement must match the other one.
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* Files must be unlocked using [UNLOCK](UNLOCK) before other programs can access them, and before the file is closed.
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* [Keywords currently not supported](Keywords-currently-not-supported-by-QB64)
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## QBasic
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* Required DOS **SHARED.EXE** to be run for QBasic to use networking access modes. No longer required.
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## See Also
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* [UNLOCK](UNLOCK)
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* [OPEN](OPEN)
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* [ACCESS](ACCESS)
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