Python Catch File Open 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 perhaps the most common kind of complaint you get while syntax for generic except clause in python you are still learning Python: >>> while True print 'Hello world' File "
Python Custom Exception
point in the line where the error was detected. The error is caused by (or at least detected at) the token preceding the arrow: in the example, the error is detected at the keyword print, since a
Python Print Exception
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 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 is nested try block possible in python exceptions are not handled by programs, however, and result in error messages as shown here: >>> 10 * (1/0) Traceback (most recent call last): File "
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Name Of Errors In Python
Stack Overflow the company Business Learn more about hiring developers or posting ads with syntax for raise clause in python us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is an exception can be in python a community of 6.2 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Python's “open()” throws different errors for “file not found” - how to handle both https://docs.python.org/2.7/tutorial/errors.html exceptions? up vote 29 down vote favorite 6 I have a script where a user is prompted to type a filename (of a file that is to be opened), and if the file doesn't exist in the current directory, the user is prompted again. Here is the short version: file = input("Type filename: ") ... try: fileContent = open(filename, "r") ... except FileNotFoundError: ... When I tested my script on http://stackoverflow.com/questions/15032108/pythons-open-throws-different-errors-for-file-not-found-how-to-handle-b my MacOS X in Python 3.3x it worked perfectly fine when I type the wrong filename on purpose (it executes the suite under "expect"). However, when I wanted to run my code on a Windows computer in Python 3.2x, I get an error that says that "FileNotFoundError" is not defined. So, Python 3.2 on Windows thinks "FileNotFoundError" is a variable and the programs quits with an error. I figured out that Python 3.2 on Windows throws an "IOError" if the input filename is not valid. I tested it on my Linux machine in Python 2.7, and it's also an IOError. My problem is now, that the code with except "FileNotFoundError": won't run on Windows's Python 3.2, but if I change it to except "IOError": it won't work on my Mac anymore. How could I work around it? The only way I can think of is to use just except, which I usually don't want. python python-3.x filenotfoundexception ioerror share|improve this question edited Feb 22 '13 at 19:57 asked Feb 22 '13 at 19:48 user2015601 6 This isn't due to Mac/Windows, it's the version of Python. I would investigate 3.2/3.3 on OS X as well (and 3.3 on Windows), consult the change logs, and then revise the
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/5627425/what-is-a-good-way-to-handle-exceptions-when-trying-to-read-a-file-in-python policies of this site About Us Learn more about Stack Overflow the company http://stackoverflow.com/questions/7777456/python-tryexceptfinally 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 in python minute: Sign up What is a good way to handle exceptions when trying to read a file in python? up vote 9 down vote favorite 2 I want to read a .csv file in python. I don't know if the file exists. My current solution is below. It feels sloppy to me because the two separate exception tests are awkwardly juxtaposed. clause in python Is there prettier way to do it? import csv fName = "aFile.csv" try: with open(fName, 'rb') as f: reader = csv.reader(f) for row in reader: pass #do stuff here except IOError: print "Could not read file:", fName python file-io exception-handling share|improve this question edited Apr 11 '11 at 21:08 asked Apr 11 '11 at 20:51 CharlesHolbrow 1,05431621 add a comment| 4 Answers 4 active oldest votes up vote 6 down vote accepted I guess I misunderstood what was being asked. Re-re-reading, it looks like Tim's answer is what you want. Let me just add this, however: if you want to catch an exception from open, then open has to be wrapped in a try. If the call to open is in the header of a with, then the with has to be in a try to catch the exception. There's no way around that. So the answer is either: "Tim's way" or "No, you're doing it correctly.". Previous unhelpful answer to which all the comments refer: import os if os.path.exists(fName): with open(fName, 'rb') as f: try: # do stuff except : # w
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company 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 minute: Sign up python try:except:finally up vote 21 down vote favorite 4 # Open new file to write file = None try: file = open(filePath, 'w') except IOError: msg = ("Unable to create file on disk.") file.close() return finally: file.write("Hello World!") file.close() The above code is ripped from a function. One of the user's system is reporting an error in line: file.write("Hello World!") error: AttributeError: 'NoneType' object has no attribute 'write' Question is, If python is failed to open given file, 'except' block executes and it has to return, but control is getting transferred to the line that is throwing given error. The value of 'file' variable is 'None'. Any pointers? python exception file-io try-catch share|improve this question edited Oct 15 '11 at 14:54 Sreenath Nannat 9911716 asked Oct 15 '11 at 11:12 user354051 1441513 add a comment| 8 Answers 8 active oldest votes up vote 41 down vote accepted You shouldn't be writing to the file in the finally block as any exceptions raised there will not be caught by the except block. The except bock executes if there is an exception raised by the try block. The finally block always executes whatever happens. Also, there shouldn't be any need for initialising the file variable to none. The use of return in the except block will not skip the finally block. By its very nature it cannot be skipped, that's why you want to put your "clean-up" code in there (i.e. closing files). So, if you want to use try:except:finally, you should be doing something like this: try: f = open("file", "w") try: f.write('Hello World!') finally: f.close()