LOF: Difference between revisions
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Created page with "The LOF function is used to find the length of an OPEN file in bytes. {{PageSyntax}} : ''totalBytes&'' = LOF([#]{{Parameter|fileNumber}}) {{PageDescription}} * LOF returns the number of bytes in an OPENed designated {{Parameter|fileNumber}}. File is empty if it returns 0. * {{Parameter|fileNumber}} is the number of the opened file. '''#''' is not required. * Often used to determine the number of records in a RANDOM access file. * Can also be used..." |
Add information on HTTP handles |
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The [[LOF]] function is used to find the length of an [[OPEN]] file in bytes. | The [[LOF]] function is used to find the length of an [[OPEN]] file in bytes, or content length of an HTTP response. | ||
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{{PageSyntax}} | {{PageSyntax}} | ||
: ''totalBytes&'' = [[LOF]]([#]{{Parameter|fileNumber}}) | : ''totalBytes&'' = [[LOF]]([#]{{Parameter|fileNumber}}) | ||
: ''totalBytes&'' = [[LOF]]([#]{{Parameter|httpHandle}}) | |||
{{PageDescription}} | {{PageDescription}} | ||
* LOF returns the number of bytes in an [[OPEN]]ed designated {{Parameter|fileNumber}}. File is empty if it returns 0. | * For regular [[OPEN]]ed files: | ||
* {{Parameter|fileNumber}} is the number of the opened file. '''#''' is not required. | ** LOF returns the number of bytes in an [[OPEN]]ed designated {{Parameter|fileNumber}}. File is empty if it returns 0. | ||
* Often used to determine the number of records in a [[RANDOM]] access file. | ** {{Parameter|fileNumber}} is the number of the opened file. '''#''' is not required. | ||
* Can also be used to avoid reading an empty file, which would create an error. | ** Often used to determine the number of records in a [[RANDOM]] access file. | ||
* LOF in '''QB64''' can return up to 9 GB (9,223,372,036 bytes) file sizes. | ** Can also be used to avoid reading an empty file, which would create an error. | ||
** LOF in '''QB64''' can return up to 9 GB (9,223,372,036 bytes) file sizes. | |||
* For HTTP handles opened using [[_OPENCLIENT]]: | |||
** [[LOF]] returns the length listed in the Content-Length header of the HTTP response. | |||
** If no Content-Length header was provided on the HTTP response, then [[LOF]] return -1 | |||
{{PageExamples}} | {{PageExamples}} | ||
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{{CodeEnd}} | {{CodeEnd}} | ||
''Example:'' Reading the Content length of an HTTP response | |||
{{CodeStart}} | |||
{{Cl|$UNSTABLE}}:Http | |||
h& = {{Cl|_OPENCLIENT}}("HTTP:https://qb64phoenix.com") | |||
{{Cl|PRINT}} {{Cl|LOF}}(h&) | |||
{{CodeEnd}} | |||
{{PageSeeAlso}} | {{PageSeeAlso}} | ||
Revision as of 07:46, 6 January 2023
The LOF function is used to find the length of an OPEN file in bytes, or content length of an HTTP response.
Syntax
Description
- For regular OPENed files:
- LOF returns the number of bytes in an OPENed designated fileNumber. File is empty if it returns 0.
- fileNumber is the number of the opened file. # is not required.
- Often used to determine the number of records in a RANDOM access file.
- Can also be used to avoid reading an empty file, which would create an error.
- LOF in QB64 can return up to 9 GB (9,223,372,036 bytes) file sizes.
- For HTTP handles opened using _OPENCLIENT:
Examples
Example: Finding the number of records in a RANDOM file using a TYPE variable.
OPEN file$ FOR RANDOM AS #1 LEN = LEN(Type_variable) NumRecords% = LOF(1) \ RecordLEN% |
Example: Reading the Content length of an HTTP response
$UNSTABLE:Http h& = _OPENCLIENT("HTTP:https://qb64phoenix.com") PRINT LOF(h&) |
See also