Eof

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EOF

Returns true when an open file has nothing left to read.

Syntax

Declare Function EOF ( ByVal filenum As Long ) As Long

Parameters

• filenum

Description

When reading from files opened for Input (File Mode), it is useful to know when the end of the file has been reached, thus avoiding errors caused by reading past the ends of files. Use EOF to determine this. EOF expects a valid file number from an already opened file. Use FreeFile to retrieve an available file file number.

For file numbers bound to files opened for Output, EOF always returns 0.

Return Value

Returns true (-1) if end-of-file has been reached, zero (0) otherwise.

Remarks

Usage

result = EOF( filenum )

Differences from QB

• In QB the comm port signaled an EOF when there were no chars waiting to be read. In QB, for files opened in RANDOM or BINARY mode, EOF returned non-zero only after a read past the end of file has been attempted. In FreeBASIC, EOF returns true after the last item is read.

See also

• LOF
• LOC
• FreeFile

Examples

'' This code finds a free file number to use and attempts to open the file

'' "file.ext" and if successful, binds our file number to the opened file. It

'' reads the file line by line, outputting it to the screen. We loop until eof()

'' returns true, in this case we ignore the loop if file is empty.

Dim As String file_name

Dim As Long file_num

file_name = "file.ext"

file_num = FreeFile( )                 '' retrieve an available file number

'' open our file and bind our file number to it, exit on error

If( Open( file_name For Input As #file_num ) ) Then

   Print "ERROR: opening file " ; file_name

   End -1

End If

Do Until EOF( file_num )               '' loop until we have reached the end of the file

   Dim As String text

   Line Input #file_num, text               '' read a line of text ...

   Print text                             '' ... and output it to the screen

Loop

Close #file_num                        '' close file via our file number

End 0

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Category: File I/O Functions
Kind: function

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Reproduced from the FreeBASIC Wiki Manual under the GNU Free Documentation License 1.3 — with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. Copyright © the FreeBASIC project and wiki contributors. See License.