物联网Python编程实战 课件 8.Python异常.pptx

Python异常江苏电子职业学院Python物联网

异常处理异常捕捉可以使用?try/except?语句概念

try/except?语句

try/except?语句importsys

try:

f=open(myfile.txt)

s=f.readline()

i=int(s.strip())

exceptOSErroraserr:

print(OSerror:{0}.format(err))

exceptValueError:

print(Couldnotconvertdatatoaninteger.)

except:

print(Unexpectederror:,sys.exc_info()[0])

raiseOSerror:[Errno2]Nosuchfileordirectory:myfile.txt1.当程序路径下没有myfile.txt文件时：ValueErrorCouldnotconvertdatatoaninteger.2.文件夹存在但是内容不能转成整数，如文件中的内容如下：

try/except...else

try/except...elseimportsys

try:

f=open(myfile.txt,r)

exceptOSErroraserr:

print(OSerror:{0}.format(err))

except:

print(Unexpectederror:,sys.exc_info()[0])

raise

else:

print(runningOk!)

try-finally语句

try-finally语句try:

str=你好

print(int(str))

exceptExceptionaserror:

print(捕获异常：+error)

else:

print(没有捕获到异常)

finally:

print(这句话，无论异常是否发生都会执行。)

抛出异常raiseraise[Exception[,args[,traceback]]]x?=?10

if?x??5:

???raise?Exception(x不能大于5。x的值为:{}.format(x))Traceback(mostrecentcalllast):Filetest.py,line3,inmoduleraiseException(x不能大于5。x的值为:{}.format(x))Exception:x不能大于5。x的值为:10

try-excepttry/except...else--finallytry/except...elseraise