open()和with open() as的区别

2020-03-18  20:37:55

open()和with open() as的区别

file = open("test.txt","r")
for line in file.readlines():
    print line
file.close()

这样直接打开文件，如果出现异常，如读取过程中文件不存在或异常，则直接出现错误，close方法无法执行，文件无法关闭

with open("test.txt","r") as file:
    for line in file.readlines():
        print line

二者的运行的结果是相同的，但是with open（）as会在语句结束自动关闭文件，即便出现异常。

file= open("test.txt","r")
try:
    for line in file.readlines():
        print line
except:
    print "error"
finally:
    file.close()

with open() as语句作用效果相当于上面的try-except-finally