This example shows two string buffers. By using the methods read and write, the stream is copied between stream_source and stream_target.
The example uses the size parameter to read a buffer of 4 bytes each time.
import io
buffer_size = 4
stream_source = io.StringIO("0123456789")
stream_target = io.StringIO()
while True:
text = stream_source.read(buffer_size)
if text == "": # read after EOF returns an empty string
print("EOF")
break
else:
print(f"read {len(text)} bytes ({text})")
stream_target.write(text)
print("target stream size", stream_target.tell())
stream_target.seek(0)
print("target stream contents", stream_target.read())
# todo: close streams or use with
Output:
read 4 bytes (0123)
read 4 bytes (4567)
read 2 bytes (89)
EOF
target stream size 10
target stream contents 0123456789