python基础-read、readline、readlines的区别

一、read([size])方法
read([size])方法从文件当前位置起读取size个字节,若无参数size,则表示读取至文件结束为止,它范围为字符串对象:
 
f = open("read.txt")
lines = f.read()
print(lines.rstrip())
print(type(lines))
f.close()
输出结果:
Hello
Welcome
What is the fuck...
<class 'str'>
 
二、readline()方法
从字面意思可以看出,该方法每次读出一行内容,所以,读取时占用内存小,比较适合大文件,该方法返回一个字符串对象:
f = open("read.txt")
line = f.readline()
print(type(line))
while line:
print(line.rstrip())
line = f.readline()
f.close()
输出结果:
<class 'str'>
Hello
Welcome
What is the fuck...
 
三、readlines()方法 
读取整个文件所有行,保存在一个列表(list)变量中,每行作为一个元素,但读取大文件会比较占内存:
f = open("read.txt")
lines = f.readlines()
print(type(lines))
for line in lines:
print(line.rstrip())
f.close()
输出结果:
<class 'list'>
Hello
Welcome
What is the fuck...
 
'decode' >>>

原文地址:https://www.cnblogs.com/Suomy/p/10028121.html