【Python】文件操作,read(), readline(), readlines()

To open a file:

open(filename, mode)

mode：

‘r’ to open for reading

'w' to open for writing

'a' to open for appending(adding to what is already in the file)

>>> file = 'C:\\Users\document.txt'   双斜杠避免被解释为转义字符

>>> filename = open(file, 'r')

>>> line = filename.readline()

>>> while line != '':
print(line)
line = filename.readline()

>>> filename.close()

when you want to process every line in a file use the for line in file approach:

for line in file:

process line

file.read(): print the whole document as a string

list = file.readlines():自动将文件分析成一个行的列表，这个列表可由python的for...in...进行处理 如，for line in file.readlines()

readline():read and return the next line from the file, including the newline character(if it exists)

return the empty string if there are no more lines in the file，每次只读取一行