Python Handling Value Error
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you have probably seen some. There are (at least) two distinguishable kinds of errors: syntax errors and exceptions. 8.1. Syntax Errors¶ Syntax errors, also known as parsing errors, are
Python Exception Class
perhaps the most common kind of complaint you get while you are still python exception message learning Python: >>> while True print('Hello world') File "
Python Exception Stack Trace
the token preceding the arrow: in the example, the error is detected at the function print(), since a colon (':') is missing before it. File name and line number are printed so you know where to look in case the input came from a script. 8.2. Exceptions¶ Even if a statement or expression is syntactically correct, it may cause an error when an attempt is
Python Print Exception
made to execute it. Errors detected during execution are called exceptions and are not unconditionally fatal: you will soon learn how to handle them in Python programs. Most exceptions are not handled by programs, however, and result in error messages as shown here: >>> 10 * (1/0) Traceback (most recent call last): File "
Pages Local Site Map ------------------------ Rename Page Delete Page ------------------------ ------------------------ Remove Spam Revert to this revision ------------------------ SlideShow User Login Handling Exceptions The simplest way to handle exceptions is with a "try-except" block: 1 (x,y) = (5,0) 2 try: 3 z = x/y 4 except ZeroDivisionError: 5 print "divide by zero" If syntax for generic except clause in python you wanted to examine the exception from code, you could have: 1 (x,y) =
Python Try Without Except
(5,0) 2 try: 3 z = x/y 4 except ZeroDivisionError as e: 5 z = e # representation: " Error: %s
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and http://stackoverflow.com/questions/5025399/python-2-7-try-and-except-valueerror policies of this site About Us Learn more about Stack Overflow the company https://www.tutorialspoint.com/python/python_exceptions.htm Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 6.2 million programmers, just like you, helping each other. Join them; it only takes a python exception minute: Sign up Python 2.7 try and except ValueError up vote 5 down vote favorite 2 I query user input which is expected to be an int by using int(raw_input(...)) However when the user doesn't enter an integer, i.e. just hits return, I get a ValueError. def inputValue(inputMatrix, rangeRows, rangeCols, defaultValue, playerValue): rowPos = int(raw_input("Please enter the row, 0 indexed.")) colPos python handling value = int(raw_input("Please enter the column, 0 indexed.")) while True: #Test if valid row col position and position does not have default value if rangeRows.count(rowPos) == 1 and rangeCols.count(colPos) == 1 and inputMatrix[rowPos][colPos] == defaultValue: inputMatrix[rowPos][colPos] = playerValue break else: print "Either the RowCol Position doesn't exist or it is already filled in." rowPos = int(raw_input("Please enter the row, 0 indexed.")) colPos = int(raw_input("Please enter the column, 0 indexed.")) return inputMatrix I tried to be smart and use try and except to catch the ValueError, print a warning to the user and then call the inputValue() again. Then it works when the user enters return to the query but falls over when the user correctly then enters an integer Below is the part of the amended code with the try and except: def inputValue(inputMatrix, rangeRows, rangeCols, defaultValue, playerValue): try: rowPos = int(raw_input("Please enter the row, 0 indexed.")) except ValueError: print "Please enter a valid input." inputValue(inputMatrix, rangeRows, rangeCols, defaultValue, playerValue) try: colPos = int(raw_input("Please enter the column, 0 indexed.")) except ValueError: print "Please enter a valid input." inputValue(inputMatrix, rangeRows, rangeCols, defaultValue, playerValue) python
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