lua-users home
lua-l archive

[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index] [Thread Index]

Can anyone explain why this code produces a line on the console that ticks up every second:

function testw()
while true do
t = os.time()
io.write(t, '\r')
end
end

As does this (with less cursor movement)

function testw()
while true do
t = os.time()
io.write(t, '\r')
while os.time() == t do
io.write('\r')  
end
end
end

But this code produces nothing:

function testw()
while true do
t = os.time()
io.write(t, '\r')
while os.time() == t do
io.write('')  
end
end
end

As does this:

function testw()
while true do
t = os.time()
io.write(t, '\r')
while os.time() == t do
end
end
end


It almost seems like an os call creates a need to flush the stdout buffer.
BTW replacing \r with \n in the lines that writes the time creates a scrolling display as expected in all cases, it seems to be some interaction with \r in particular.

On the other hand this:

function testw()
while true do
t = os.time()
io.write(t, '\r')
os.execute('sleep 1')
io.write('\r')
end
end

does not work either so an extra write to flush the buffer is not enough.





Jose Torre-Bueno