How can I use try-except to deal with an error?
Thank you :)
eva yang 0 Newbie Poster
snippsat 661 Master Poster
vegaseat 1,735 DaniWeb's Hypocrite Team Colleague
For example, you are trying to open a file that does not exist.
This code will give you a Traceback IOError and the program exits ...
fname = "xyz.txt"
fin = open(fname, "r")
"""my output (if xyz.txt does not exist) -->
Traceback (most recent call last):
File "error_fname1.py", line 2, in <module>
fin = open(fname, "r")
IOError: [Errno 2] No such file or directory: 'xyz.txt'
"""You can trap the error and do something else that would avoid the program exit, if you want to ...
fname = "xyz.txt"
try:
fin = open(fname, "r")
except:
print( "Cannot find file %s" % fname )
# do something else here
"""my output (if xyz.txt does not exist) -->
Cannot find file xyz.txt
"""You can be more specific and include the type of error ...
fname = "xyz.txt"
try:
fin = open(fname, "r")
except IOError:
print( "Cannot find file %s" % fname )
# do something else here
"""my output (if xyz.txt does not exist) -->
Cannot find file xyz.txt
"""Even more specific with type of error and error message ...
fname = "xyz.txt"
try:
fin = open(fname, "r")
# Python2
#except IOError, which_error:
# Python3
except IOError as which_error:
print( "Unable to open file: %s" % which_error )
# do something else here
"""my output (if xyz.txt does not exist) -->
Unable to open file: [Errno 2] No such file or directory: 'xyz.txt'
""" eva yang 0 Newbie Poster
Thank you so much!It helps a lot
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