Weird behaviour with File.eof

[Daniel Kozák via Digitalmars-d-learn]

V Sun, 20 Sep 2015 20:17:36 +0000
Dandyvica via Digitalmars-d-learn <digitalmars-d-learn at puremagic.com>
napsáno:

> Hi all,
> 
> I can't explain to myself this weird behavior:
> 
> void main(string[] argv)
> {
> 	char[] line;
> 	auto fh = File(argv[1]);
> 	while (!fh.eof) {
> 		writef("before readln eof=%s, ", fh.eof);
> 		fh.readln(line,std.ascii.newline);
> 		writefln("line=<%s>, after readln
> eof=%s",chomp(line), fh.eof); }
> 	fh.close();
> }
> 
> My file is made of 10 lines:
> 
> 
> cat numbers.txt
> 1
> 2
> 3
> 4
> 5
> 6
> 7
> 8
> 9
> 10
> 
> ╰─$ wc -l numbers.txt
> 10 numbers.txt
> 
> When run:
> 
> before readln eof=false, line=<1>, after readln eof=false
> before readln eof=false, line=<2>, after readln eof=false
> before readln eof=false, line=<3>, after readln eof=false
> before readln eof=false, line=<4>, after readln eof=false
> before readln eof=false, line=<5>, after readln eof=false
> before readln eof=false, line=<6>, after readln eof=false
> before readln eof=false, line=<7>, after readln eof=false
> before readln eof=false, line=<8>, after readln eof=false
> before readln eof=false, line=<9>, after readln eof=false
> before readln eof=false, line=<10>, after readln eof=false
> before readln eof=false, line=<>, after readln eof=true
> 
> I can't explain why eof is not set to true after reading the last 
> line ?!
> 
> Last DMD 2.68.1.0, Linux Mint 17.2.
> 
> 
> Thanks for any clue.

This is normal behavior

http://www.cplusplus.com/reference/cstdio/feof/

"Notice that stream's internal position indicator may point to the
end-of-file for the next operation, but still, the end-of-file
indicator may not be set until an operation attempts to read at that
point."