Convert exception error to string

Question

I want to work with the error message from an exception but can’t seem to convert it to a string. I’ve read the os library man page but something is not clicking for me.

Printing the error works:

try:
    os.open("test.txt", os.O_RDONLY)
except OSError as err:
    print ("I got this error: ", err)

But this does not:

try:
    os.open("test.txt", os.O_RDONLY)
except OSError as err:
    print ("I got this error: " + err)

TypeError: Can't convert 'FileNotFoundError' object to str implicitly

Asked By: dpetican

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Source

Answer 1

From the docs for print()

All non-keyword arguments are converted to strings like str() does and written to the stream

So in the first case, your error is converted to a string by the print built-in, whereas no such conversion takes place when you just try and concatenate your error to a string. So, to replicate the behavior of passing the message and the error as separate arguments, you must convert your error to a string with str().

Answered By: miradulo

Answer 2

In my experience what you want is repr(err), which will return both the exception type and the message.

str(err) only gives the message.

Answered By: Hendy Irawan

Convert exception error to string

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