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eof

eof(stream) -> Bool

Tests whether an I/O stream is at end-of-file. If the stream is not yet exhausted, this function will block to wait for more data if necessary, and then return false. Therefore it is always safe to read one byte after seeing eof return false. eof will return false as long as buffered data is still available, even if the remote end of a connection is closed.

Examples

julia> io = IOBuffer("Julia is awesome!")
IOBuffer(data=UInt8[...], readable=true, writable=true, seekable=true, append=false, size=18, maxsize=Inf, ptr=1, mark=-1)

julia> eof(io)
false

In this example, the eof function is used to check if an IOBuffer named io is at the end-of-file. Since the buffer still contains data, eof returns false.

julia> io = IOBuffer("Hello, World!")
IOBuffer(data=UInt8[...], readable=true, writable=true, seekable=true, append=false, size=13, maxsize=Inf, ptr=1, mark=-1)

julia> read(io, Char)
'H'

julia> read(io, Char)
'e'

julia> read(io, Char)
'l'

julia> read(io, Char)
'l'

julia> read(io, Char)
'o'

julia> eof(io)
false

In this example, characters are read from the IOBuffer io using the read function. After reading multiple characters, eof is called, and it still returns false because there is more data available in the buffer.

julia> io = IOBuffer("")
IOBuffer(data=UInt8[...], readable=true, writable=true, seekable=true, append=false, size=0, maxsize=Inf, ptr=1, mark=-1)

julia> eof(io)
true

Here, eof is used to check if an empty IOBuffer named io is at the end-of-file. Since there is no data in the buffer, eof returns true.

julia> file = open("data.txt", "r")
IOStream(<file data.txt>)

julia> eof(file)
false

In this example, the eof function is used to check if an IOStream named file is at the end-of-file. Since there is more data available in the file, eof returns false.

julia> file = open("data.txt", "r")
IOStream(<file data.txt>)

julia> read(file, String)
"Hello, World!"

julia> eof(file)
true

In this example, data is read from the IOStream file using the read function. After reading the contents of the file, eof is called, and it returns true because there is no more data to read.

Common mistake example:

julia> io = IOBuffer("Julia is awesome!")
IOBuffer(data=UInt8[...], readable=true, writable=true, seekable=true, append=false, size=18, maxsize=Inf, ptr=1, mark=-1)

julia> eof(io)
true

In this example, the eof function is mistakenly used to check if there is more data available in the IOBuffer io. However, since the buffer still contains data, the correct output should be false.

See Also

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