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chapter
- Python Introduction
- Python development environment to build
- Python syntax
- Python variables
- Python Value Type
- Python type conversion
- Python String (String)
- Operators Python
- Python list (list)
- Python tuples (Tuple)
- Python collection (Set)
- Python dictionary (Dictionary)
- Python If … Else
- Python While loop
- Python For loop
- Python functions
- Python Lambda
- Python Classes and Objects
- Python inheritance
- Python iterator (Iterator)
- Python module
- Python date (Datetime)
- Python JSON
- Python regular expression (RegEx)
- Python PIP package manager
- Python exception handling (Try ... Except)
- Python Open File (File Open)
- Python read file
- Python write file
- Python delete files and folders
tryBlock so that you can detect errors in the code block.
exceptBlock so that you can handle the error.
finallyBlock so that you can execute the final code, regardless of trythe exceptoutcome of the block, finallycode block will be executed.
Exception Handling
When an error (or abnormal) occurs, Python will usually stop the execution and error.
These exceptions can use try/ exceptstatement processing:
Examples
The following tryblock exception is generated, because xthere is no definition:
try:
print(x)
except:
print("发生异常")
Because the tryblock error is raised, so the exceptblock will be executed.
If you do not tryblock, the program will crash and raise an error:
Examples
This statement generates an error because xthere is no definition:
print(x)
Except more
May define a plurality of except, for example, may be defined as a special error code blocks except a special:
Examples
This statement generates an error because xthere is no definition:
try:
print(x)
except NameError:
print("变量x没有定义")
except:
print("其他错误")
else
Can use elsekeyword to define a code block, if no error occurs, elsethe code block is executed:
Examples
In this example, try block does not produce any error:
try:
print("你好")
except:
print("出错了")
else:
print("一切正常")
finally
If you define a finallyblock, regardless of trywhether the block error is raised, it will execute finallythe block.
Examples
try:
print(x)
except:
print("出错了")
finally:
print("'try except'处理结束")
This is useful for close objects, cleaning up resources:
Examples
Try not to write a document written:
try:
f = open("test.txt")
f.write("奇客谷教程")
except:
print("写文件出错了")
finally:
f.close() # 关闭文件
The file is closed.