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EOFfunction
Checks to see if the end of an open file has been reached
Syntax
Declare Function EOF ( ByVal filenum As Long ) As LongParameters
| Name | Description | |
|---|---|---|
filenum | File number of an open file. |
Return value
Returns true (-1) if end-of-file has been reached, zero (0) otherwise.
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.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
Example
'' 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
Reference
- Documented in KeyPgEof.html