LOCK (access): Difference between revisions
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* [[LOCK]] and [[UNLOCK]] statements are always used in pairs and each statement must match the other one. | * [[LOCK]] and [[UNLOCK]] statements are always used in pairs and each statement must match the other one. | ||
* Files must be unlocked using [[UNLOCK]] before other programs can access them, and before the file is closed. | * Files must be unlocked using [[UNLOCK]] before other programs can access them, and before the file is closed. | ||
* [[ | * '''[[Keywords currently not supported by QB64#Keywords_not_supported_in_Linux_or_macOS_versions|Keyword not supported in Linux or macOS versions]]''' | ||
=== QBasic/QuickBASIC === | |||
==QBasic/QuickBASIC== | |||
* Required DOS '''SHARED.EXE''' to be run for QBasic to use networking access modes. No longer required. | * Required DOS '''SHARED.EXE''' to be run for QBasic to use networking access modes. No longer required. | ||
Latest revision as of 02:03, 28 January 2023
The LOCK statement restricts access to parts of a file by other programs or processes.
Syntax
Description
- fileNumber% is the file number of the file to lock.
- In the first syntax, the entire file is locked.
- In the second syntax, record& is the record number of the file to lock.
- 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).
- For files opened in BINARY mode, each record corresponds to a single byte.
- LOCK and UNLOCK statements are always used in pairs and each statement must match the other one.
- Files must be unlocked using UNLOCK before other programs can access them, and before the file is closed.
- Keyword not supported in Linux or macOS versions
QBasic/QuickBASIC
- Required DOS SHARED.EXE to be run for QBasic to use networking access modes. No longer required.
See also