本文主要是介绍python try/except/finally的用法,希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!
稍微总结一下,否则总是忘。
- x = 'abc'
- def fetcher(obj, index):
- return obj[index]
-
- fetcher(x, 4)
输出:
- File "test.py", line 6, in <module>
- fetcher(x, 4)
- File "test.py", line 4, in fetcher
- return obj[index]
- IndexError: string index out of range
第一: try不仅捕获异常,而且会恢复执行
- def catcher():
- try:
- fetcher(x, 4)
- except:
- print "got exception"
- print "continuing"
输出:
第二:无论try是否发生异常,finally总会执行
- def catcher():
- try:
- fetcher(x, 4)
- finally:
- print 'after fecth'
输出:
- after fecth
- Traceback (most recent call last):
- File "test.py", line 55, in <module>
- catcher()
- File "test.py", line 12, in catcher
- fetcher(x, 4)
- File "test.py", line 4, in fetcher
- return obj[index]
- IndexError: string index out of range
第三:try无异常,才会执行else
- def catcher():
- try:
- fetcher(x, 4)
- except:
- print "got exception"
- else:
- print "not exception"
输出:
- def catcher():
- try:
- fetcher(x, 2)
- except:
- print "got exception"
- else:
- print "not exception"
输出:
else作用:没有else语句,当执行完try语句后,无法知道是没有发生异常,还是发生了异常并被处理过了。通过else可以清楚的区分开。
第四:利用raise传递异常
- def catcher():
- try:
- fetcher(x, 4)
- except:
- print "got exception"
- raise
输出:
- got exception
- Traceback (most recent call last):
- File "test.py", line 37, in <module>
- catcher()
- File "test.py", line 22, in catcher
- fetcher(x, 4)
- File "test.py", line 4, in fetcher
- return obj[index]
- IndexError: string index out of range
raise语句不包括异常名称或额外资料时,会重新引发当前异常。如果希望捕获处理一个异常,而又不希望
异常在程序代码中消失,可以通过raise重新引发该异常。
第五:except(name1, name2)
- def catcher():
- try:
- fetcher(x, 4)
- except(TypeError, IndexError):
- print "got exception"
- else:
- print "not exception"
捕获列表列出的异常,进行处理。若except后无任何参数,则捕获所有异常。
- def catcher():
- try:
- fetcher(x, 4)
- except:
- print "got exception"
这篇关于python try/except/finally的用法的文章就介绍到这儿,希望我们推荐的文章对编程师们有所帮助!