实例

如果语句引发错误，则打印 "Something went wrong"：

try:
  x > 3
except:
  print("Something went wrong")

完整实例：

# (x > 3) will raise an error because x is not defined:
try:
  x > 3
except:
  print("Something went wrong")
print("Even if it raised an error, the program keeps running")

定义和用法

在 try ... except 块中使用了关键字 except。它定义 try 块引发错误时要运行的代码块。

您可以为不同的错误类型定义不同的块，以及没有问题的情况下执行的块，请参见下面的例子。

更多实例

实例 1

如果引发 NameError 则写一条消息，如果引发 TypeError 则写另一条：

x = "hello"
try:
  x > 3
except NameError:
  print("You have a variable that is not defined.")
except TypeError:
  print("You are comparing values of different type")

完整实例：

# (x > 3) will raise an error because x is a string and 3 is a number, and cannot be compared using a '>':
x = "hello"
try:
  x > 3
except NameError:
  print("You have a variable that is not defined.")
except TypeError:
  print("You are comparing values of different type")

实例 2

尝试执行一条引发错误的语句，但没有定义的错误类型（在这种情况下为 ZeroDivisionError）：

try:
  x = 1/0
except NameError:
  print("You have a variable that is not defined.")
except TypeError:
  print("You are comparing values of different type")
except:
  print("Something else went wrong")

完整实例：

# (x/0) raises a ZeroDivisionError:
try:
  x = 1/0
except NameError:
  print("You have a variable that is not defined.")
except TypeError:
  print("You are comparing values of different type")
except:
  print("Something else went wrong")

实例 3

如果没有出现错误，写一条消息：

x = 1
try:
  x > 10
except NameError:
  print("You have a variable that is not defined.")
except TypeError:
  print("You are comparing values of different type")
else:
  print("The 'Try' code was executed without raising any errors!")

完整实例：

# (x > 10) will not raise any errors:
x = 1
try:
  x > 10
except NameError:
  print("You have a variable that is not defined.")
except TypeError:
  print("You are comparing values of different type")
else:
  print("The 'Try' code was executed without raising any errors!")

相关页面

try 关键字

finally 关键字