Python error, debugging

1. Error handling

Use try except finally

Try :     = 10/0except  zerodivisionerror, E:    print"zerodivisionerror  ", Efinally:    print"finally "

or modulo by zerofinally

Error type (with warning)

baseexception+--Systemexit+--Keyboardinterrupt+--Generatorexit+--Exception+--stopiteration+--StandardError| +--Buffererror| +--Arithmeticerror|    | +--Floatingpointerror|    | +--Overflowerror|    | +--Zerodivisionerror| +--Assertionerror| +--Attributeerror| +--EnvironmentError|    | +--IOError|    | +--OSError|         | +--windowserror (Windows)|         | +--vmserror (VMS)| +--Eoferror| +--Importerror| +--Lookuperror|    | +--Indexerror|    | +--Keyerror| +--Memoryerror| +--Nameerror|    | +--Unboundlocalerror| +--Referenceerror| +--RuntimeError|    | +--Notimplementederror| +--SyntaxError|    | +--Indentationerror|         | +--Taberror| +--Systemerror| +--TypeError| +--ValueError| +--Unicodeerror| +--Unicodedecodeerror| +--Unicodeencodeerror| +--Unicodetranslateerror+--Warning+--deprecationwarning+--pendingdeprecationwarning+--runtimewarning+--syntaxwarning+--userwarning+--futurewarning+--importwarning+--unicodewarning+--byteswarning

Logging Module Logging error messages

ImportLoggingdefTest (i):Try: J= 10/IexceptStandardError, E:Print "StandardError"logging.exception (e)Print "Test"Test (0)Print "End"

or modulo by Zerotestendtraceback (most recent call last):   " f:/pyproject/test2.py " inch Test     = 10/or modulo by zero

Custom error types inherit built-in error types

Class Fooerror (StandardError):
    Pass


def foo (s):
    n = Int (s)
    if n = = 0:
        Raise Fooerror ("value is%s"% s)


Foo ("0")

Traceback (most recent): File"f:/pyproject/test2.py", Line 18,inch<module>Foo ("0") File"f:/pyproject/test2.py", line 15,inchFooRaiseFooerror ("value is%s"%s)__main__. Fooerror:value is0

You can also use raise to throw an error to the top-level caller after you catch an error in except

2. Commissioning

Assert assertion

 def   foo (n): I  = int (n)  assert  i! = 0, "  catch assert   "  return   ia  = foo ( " 0  "  )  print  a 

 traceback (most recent call last): File   f:/pyproject/test2.py   ", line 13, Span style= "COLOR: #0000ff" >in  <module> a  = foo ("  0   " ) File   " f:/ pyproject/test2.py  , line ten, in  Span style= "COLOR: #000000" > foo  assert  i! = 0,  " catch assert  " 
 Assertionerror:catch Assert 
  

Equivalent if I! = 0 is true continue execution conversely throw assertionerror and interrupt run

To turn off the Assert method is to add the parameter-O to the Python interpreter to compile the python into a pyo file

Logging will not throw an error but will hit the log the default logging level is warning to modify the default value by Logging.basicconfig (level=logging. Log level)

The logging module prints the logs to standard output and only displays logs that are greater than or equal to the set level (log level level critical > ERROR > WARNING > INFO > DEBUG >notset)

The default format is Logger: output content

Launch the Python debugger pdb, let the program run in a single step, can view the running state at any time

After starting the program with a parameter -m pdb , the PDB navigates to the code to be executed next. Enter a command l to view the code. You can enter a command at any time p 变量名 to view the variable.

Pdb.set_trace () This method also uses the PDB, but does not need to step the execution, we only need import pdb , then, in the possible error place one pdb.set_trace() , can set a breakpoint, the line code, the program automatically pdb.set_trace() pauses and enters the PDB debugging environment, can use the command pview variables or continue running with a command c

Python error, debugging