a buffer file open function

# When the file is written annotations hardware, system calls, such I / O operations are typically very long time 
# To reduce I / O operation frequency, typically using a buffer file (before there is sufficient data for the system call) 
# File buffering behavior is divided into: 
# full buffer: buffering open function is provided an integer greater than 1, n, n being the buffer size 
# line buffer: buffering open function set to 1, as long as the encounter \ n outputs general procedure for the terminal 
# unbuffered: buffering function is set to zero open to a handle a 
# Python default number of bytes buffer full 4096 

F = open ( " test.txt " , " W " , buffering = 1024)   # fully buffered 
f = Open ( " test.txt " , " W " , buffering =. 1)   # line buffer 
F = Open ( "test.txt", "w", buffering=0)  # 无缓冲
f.write("$" * 1024)
f.write("abc\n")  # 遇到\n就输出
f.write("$")
f.close()