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49 lines
2.2 KiB
Plaintext
49 lines
2.2 KiB
Plaintext
#REDIRECT [[OPEN#File_Access_Modes]]
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The '''INPUT''' file mode in an [[OPEN]] statement opens an existing file for [[INPUT (file statement)|INPUT]].
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{{PageSyntax}}
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: [[OPEN]] {{Parameter|fileName$}} FOR '''INPUT''' AS #filenumber%
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* If {{Parameter|fileName$}} does not exist, attempting to open it FOR INPUT will create a program [[ERROR Codes|file error]]. Use [[_FILEEXISTS]] to avoid errors.
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* The file number can be determined automatically by using a [[FREEFILE]] variable value.
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* Mode can use [[INPUT (file statement)|INPUT]] #, [[LINE INPUT (file statement)|LINE INPUT]] # or [[INPUT$]] to read the file data.
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* Use the [[EOF]] function to avoid reading data past the end of a file and creating an [[ERROR Codes|INPUT error]].
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* Input file statements will use the same file number as the OPEN statement.
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* The INPUT mode allows the same file to be opened in another mode with a different number.
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* '''NOTE: [[LINE INPUT (file statement)|LINE INPUT]] will work faster in [[BINARY]] than INPUT mode in QB64 to stay compatible with QBasic.'''
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{{PageExamples}}
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''Example:'' Avoiding an INPUT mode or [[INPUT (file statement)|INPUT #]] read error using a FileExist function. QB64 can use the [[_FILEEXISTS]] function.
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{{CodeStart}} '' ''
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DIM Fdata$(100)
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INPUT "Enter data file name: ", datafile$
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IF _FILEEXISTS(datafile$) THEN
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D% = {{Cl|FREEFILE}}: count = 0
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{{Cl|OPEN}} datafile$ FOR {{Cl|INPUT (file mode)|INPUT}} AS #D%
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DO UNTIL {{Cl|EOF}}(D%)
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count = count + 1
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{{Cl|INPUT (file statement)|LINE INPUT}} #D%, Fdata$(count)
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IF count = 100 THEN {{Cl|EXIT}} DO ' don't exceed {{Cl|Arrays|array}} size!
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LOOP
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{{Cl|CLOSE}} #D%
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ELSE : PRINT "File not found!"
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END IF
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{{CodeEnd}}
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: ''Explanation:'' The [[_FILEEXISTS]] function is used before {{InlineCode}}OPEN datafile$ FOR INPUT AS #D%{{InlineCodeEnd}}, which would generate an error in case the file didn't exist.
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{{PageSeeAlso}}
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* [[INPUT (file statement)|INPUT #]], [[LINE INPUT (file statement)|LINE INPUT #]], [[INPUT$]] {{text|(file input)}}
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* [[INPUT]], [[LINE INPUT]], [[INPUT$]] {{text|(keyboard input)}}
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* [[APPEND]], [[RANDOM]], [[OUTPUT]], [[BINARY]]
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* [[READ]], [[DATA]]
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* [[_FILEEXISTS]], [[_DIREXISTS]]
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{{PageNavigation}}
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