What three methods does python provide for reading the contents of text files?

The three methods are: "read()", "readline()", and "readlines()". "read()" reads all the contents of the file at once and puts it into a large string; "readline()" reads the text line by line; "readlines()" reads all the contents of the text at once.

There are three methods for python to read the contents of a text file.

read(), readline(), readlines()

read()

read() It is the simplest method to read all the contents of the file at once and put it in a large string, that is, in memory.

file=open('test.txt')try:
    file_context=file.read()  
    #file_context是一个string，读取完后，就失去了对test.txt的文件引用
    #file_context=open(file).read().splitlines()，则
    #file_context是一个list，每行文本内容是list中的一个元素finally:
    file.close()12345678

Advantages of read(): convenient, simple, one-time reading of the file into a large string, the fastest.

Disadvantages of read(): When the file is too large, it will occupy too much memory

readline()

readline() one by one Read text line by line, the result is a list

with open(file) as f:
    line=f.readline()    while line:        print line
        line=f.readline()12345

Advantages of readline(): small memory usage, read line by line

Disadvantages of readline(): read line by line, The speed is relatively slow

readlines()

readlines() reads all the contents of the text at once, and the result is a list

with open(file) as f:
    for line in f.readlines(): 
       print line#这种方法读取的文本内容，每行文本末尾都会带一个'\n'换行符，可以使用L.rstrip('\n')去掉1234

readlines() Advantages: Reading the text content at one time is relatively fast. Disadvantages of readlines(): As the text increases, it will occupy more and more memory.

file=open('test.txt','r')try:    for line in file:        print line
 finalli:
     file.close()

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