blocks|key|1229471|text|对于Python+2.6及更高版本和Python+3.x：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1229472|except+Exception+as+e:+print(e)|code-block|syntax|javascript|1229473|对于Python+2.5和更早版本，请使用：|1229474|except+Exception,e:+print+str(e)|1229475|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

For Python 2.6 and later and Python 3.x:

<pre><code>except Exception as e: print(e)
</code></pre>

For Python 2.5 and earlier, use:

<pre><code>except Exception,e: print str(e)
</code></pre>

blocks|key|1444453|text|traceback模块为formatting+and+printing+exceptions及其回溯提供了方法，例如，这将像默认处理程序一样打印异常：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1444454|import+traceback

try:
++++1/0
except+Exception:
++++traceback.print_exc()|code-block|syntax|javascript|1444455|输出：|1444456|Traceback+(most+recent+call+last):
++File+"C:\scripts\divide_by_zero.py",+line+4,+in+<module>
++++1/0
ZeroDivisionError:+division+by+zero|1444457|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.python.org/library/traceback.html|1|https://docs.python.org/3/library/traceback.html#traceback-examples^0|0|9|0|9|0|C|Y|1|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@$9|11|A|12|1|13]|$9|14|A|15|1|16]]|E|$]]|$1|F|3|G|5|H|7|17|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|18|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|19|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|1A|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]|W|$5|R|S|T|E|$U|X]]]]

The <a href="http://docs.python.org/library/traceback.html" rel="noreferrer"><code>traceback</code></a> module provides methods for <a href="https://docs.python.org/3/library/traceback.html#traceback-examples" rel="noreferrer">formatting and printing exceptions</a> and their tracebacks, e.g. this would print exception like the default handler does:

<pre><code>import traceback

try:
 1/0
except Exception:
 traceback.print_exc()
</code></pre>

Output:

<pre><code>Traceback (most recent call last):
 File "C:\scripts\divide_by_zero.py", line 4, in &lt;module&gt;
 1/0
ZeroDivisionError: division by zero
</code></pre>

blocks|key|1444388|text|如果你想传递错误字符串，这里有一个来自Errors+and+Exceptions+(Python2.6)的例子。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1444389|>>>+try:
...++++raise+Exception('spam',+'eggs')
...+except+Exception+as+inst:
...++++print+type(inst)+++++#+the+exception+instance
...++++print+inst.args++++++#+arguments+stored+in+.args
...++++print+inst+++++++++++#+__str__+allows+args+to+printed+directly
...++++x,+y+=+inst++++++++++#+__getitem__+allows+args+to+be+unpacked+directly
...++++print+'x+=',+x
...++++print+'y+=',+y
...
<type+'exceptions.Exception'>
('spam',+'eggs')
('spam',+'eggs')
x+=+spam
y+=+eggs|code-block|syntax|javascript|1444390|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.python.org/tutorial/errors.html^0|J|L|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

In case you want to pass error strings, here is an example from <a href="http://docs.python.org/tutorial/errors.html" rel="noreferrer">Errors and Exceptions</a> (Python 2.6)

<pre><code>&gt;&gt;&gt; try:
... raise Exception('spam', 'eggs')
... except Exception as inst:
... print type(inst) # the exception instance
... print inst.args # arguments stored in .args
... print inst # __str__ allows args to printed directly
... x, y = inst # __getitem__ allows args to be unpacked directly
... print 'x =', x
... print 'y =', y
...
&lt;type 'exceptions.Exception'&gt;
('spam', 'eggs')
('spam', 'eggs')
x = spam
y = eggs
</code></pre>

blocks|key|1229587|text|(我本打算对@jldupont的回答发表评论，但我没有足够的名气。)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1229588|我在其他地方也看到过类似@jldupont的答案。顺便说一下，我认为重要的是要注意这一点：|1229589|except+Exception+as+e:
++++print(e)|code-block|syntax|javascript|1229590|默认情况下，会将错误输出打印到sys.stdout。一般而言，更合适的错误处理方法是：|offset|length|style|CODE|1229591|except+Exception+as+e:
++++print(e,+file=sys.stderr)|1229592|(请注意，您必须使用import+sys才能正常工作。)这样，错误被打印到STDERR而不是STDOUT，这允许正确的输出解析/重定向/等等。我理解问题严格地是关于“打印错误”，但似乎重要的是指出这里的最佳实践，而不是遗漏这个细节，这可能会导致任何最终学不到更好的人的非标准代码。|1229593|我没有像在Cat+Plus的答案中那样使用traceback模块，也许这是最好的方法，但我想我应该把它抛出去。|1229594|entityMap^0|0|0|0|F|A|0|0|A|A|11|6|1A|6|0|L|9|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|Z|8|@$K|10|L|11|M|N]]|9|@]|A|$]]|$1|O|3|P|5|F|7|12|8|@]|9|@]|A|$G|H]]|$1|Q|3|R|5|6|7|13|8|@$K|14|L|15|M|N]|$K|16|L|17|M|N]|$K|18|L|19|M|N]]|9|@]|A|$]]|$1|S|3|T|5|6|7|1A|8|@$K|1B|L|1C|M|N]]|9|@]|A|$]]|$1|U|3|-4|5|6|7|1D|8|@]|9|@]|A|$]]]|V|$]]

(I was going to leave this as a comment on @jldupont's answer, but I don't have enough reputation.)

I've seen answers like @jldupont's answer in other places as well. FWIW, I think it's important to note that this:

<pre class="lang-py prettyprint-override"><code>except Exception as e:
 print(e)
</code></pre>

will print the error output to <code>sys.stdout</code> by default. A more appropriate approach to error handling in general would be:

<pre><code>except Exception as e:
 print(e, file=sys.stderr)
</code></pre>

(Note that you have to <code>import sys</code> for this to work.) This way, the error is printed to <code>STDERR</code> instead of <code>STDOUT</code>, which allows for the proper output parsing/redirection/etc. I understand that the question was strictly about 'printing an error', but it seems important to point out the best practice here rather than leave out this detail that could lead to non-standard code for anyone who doesn't eventually learn better.

I haven't used the <code>traceback</code> module as in Cat Plus Plus's answer, and maybe that's the best way, but I thought I'd throw this out there.

blocks|key|1229638|text|在捕获异常时，可以很好地控制回溯跟踪中的哪些信息要显示/记录。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1229639|代码|1229640|with+open("not_existing_file.txt",+'r')+as+text:
++++pass|code-block|syntax|javascript|1229641|将产生以下回溯：|1229642|Traceback+(most+recent+call+last):
++File+"exception_checks.py",+line+19,+in+<module>
++++with+open("not_existing_file.txt",+'r')+as+text:
FileNotFoundError:+[Errno+2]+No+such+file+or+directory:+'not_existing_file.txt'|1229643|打印/记录完整回溯|1229644|正如其他人已经提到的，您可以通过使用traceback模块捕获整个回溯：|1229645|import+traceback
try:
++++with+open("not_existing_file.txt",+'r')+as+text:
++++++++pass
except+Exception+as+exception:
++++traceback.print_exc()|1229646|这将产生以下输出：|1229647|Traceback+(most+recent+call+last):
++File+"exception_checks.py",+line+19,+in+<module>
++++with+open("not_existing_file.txt",+'r')+as+text:
FileNotFoundError:+[Errno+2]+No+such+file+or+directory:+'not_existing_file.txt'|1229648|您可以通过使用日志记录来实现相同的目的：|1229649|try:
++++with+open("not_existing_file.txt",+'r')+as+text:
++++++++pass
except+Exception+as+exception:
++++logger.error(exception,+exc_info=True)|1229650|输出：|1229651|__main__:+2020-05-27+12:10:47-ERROR-+[Errno+2]+No+such+file+or+directory:+'not_existing_file.txt'
Traceback+(most+recent+call+last):
++File+"exception_checks.py",+line+27,+in+<module>
++++with+open("not_existing_file.txt",+'r')+as+text:
FileNotFoundError:+[Errno+2]+No+such+file+or+directory:+'not_existing_file.txt'|1229652|仅打印/记录错误名称/消息|1229653|您可能对整个回溯不感兴趣，但只对最重要的信息感兴趣，例如异常名称和异常消息，使用：|1229654|try:
++++with+open("not_existing_file.txt",+'r')+as+text:
++++++++pass
except+Exception+as+exception:
++++print("Exception:+{}".format(type(exception).__name__))
++++print("Exception+message:+{}".format(exception))|1229655|1229656|Exception:+FileNotFoundError
Exception+message:+[Errno+2]+No+such+file+or+directory:+'not_existing_file.txt'|1229657|entityMap^0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1G|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|1H|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|1I|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|1J|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|1K|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|1L|8|@]|9|@]|A|$]]|$1|Q|3|R|5|F|7|1M|8|@]|9|@]|A|$G|H]]|$1|S|3|T|5|6|7|1N|8|@]|9|@]|A|$]]|$1|U|3|V|5|F|7|1O|8|@]|9|@]|A|$G|H]]|$1|W|3|X|5|6|7|1P|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|F|7|1Q|8|@]|9|@]|A|$G|H]]|$1|10|3|11|5|6|7|1R|8|@]|9|@]|A|$]]|$1|12|3|13|5|F|7|1S|8|@]|9|@]|A|$G|H]]|$1|14|3|15|5|6|7|1T|8|@]|9|@]|A|$]]|$1|16|3|17|5|6|7|1U|8|@]|9|@]|A|$]]|$1|18|3|19|5|F|7|1V|8|@]|9|@]|A|$G|H]]|$1|1A|3|11|5|6|7|1W|8|@]|9|@]|A|$]]|$1|1B|3|1C|5|F|7|1X|8|@]|9|@]|A|$G|H]]|$1|1D|3|-4|5|6|7|1Y|8|@]|9|@]|A|$]]]|1E|$]]

One has pretty much control on which information from the traceback to be displayed/logged when catching exceptions.

The code

<pre><code>with open("not_existing_file.txt", 'r') as text:
 pass
</code></pre>

would produce the following traceback:

<pre><code>Traceback (most recent call last):
 File "exception_checks.py", line 19, in &lt;module&gt;
 with open("not_existing_file.txt", 'r') as text:
FileNotFoundError: [Errno 2] No such file or directory: 'not_existing_file.txt'
</code></pre>

<h2>Print/Log the full traceback</h2>

As others already mentioned, you can catch the whole traceback by using the traceback module:

<pre><code>import traceback
try:
 with open("not_existing_file.txt", 'r') as text:
 pass
except Exception as exception:
 traceback.print_exc()
</code></pre>

This will produce the following output:

<pre><code>Traceback (most recent call last):
 File "exception_checks.py", line 19, in &lt;module&gt;
 with open("not_existing_file.txt", 'r') as text:
FileNotFoundError: [Errno 2] No such file or directory: 'not_existing_file.txt'
</code></pre>

You can achieve the same by using logging:

<pre><code>try:
 with open("not_existing_file.txt", 'r') as text:
 pass
except Exception as exception:
 logger.error(exception, exc_info=True)
</code></pre>

Output:

<pre><code>__main__: 2020-05-27 12:10:47-ERROR- [Errno 2] No such file or directory: 'not_existing_file.txt'
Traceback (most recent call last):
 File "exception_checks.py", line 27, in &lt;module&gt;
 with open("not_existing_file.txt", 'r') as text:
FileNotFoundError: [Errno 2] No such file or directory: 'not_existing_file.txt'
</code></pre>

<h2>Print/log error name/message only</h2>

You might not be interested in the whole traceback, but only in the most important information, such as Exception name and Exception message, use:

<pre><code>try:
 with open("not_existing_file.txt", 'r') as text:
 pass
except Exception as exception:
 print("Exception: {}".format(type(exception).__name__))
 print("Exception message: {}".format(exception))
</code></pre>

Output:

<pre><code>Exception: FileNotFoundError
Exception message: [Errno 2] No such file or directory: 'not_existing_file.txt'
</code></pre>

blocks|key|1444644|text|在"except+as+e:“解决方案的基础上，扩展了一个很好的一行，它包含一些额外的信息，比如错误的类型和发生的位置。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1444645|try:
++++1/0
except+Exception+as+e:
++++print(f"{type(e).__name__}+at+line+{e.__traceback__.tb_lineno}+of+{__file__}:+{e}")|code-block|syntax|javascript|1444646|输出：|1444647|ZeroDivisionError+at+line+48+of+/Users/.../script.py:+division+by+zero|1444648|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Expanding off of the &quot;except Exception as e:&quot; solution here is a nice one liner which includes some additional info like the type of error and where it occurred.
<pre class="lang-py prettyprint-override"><code>
try:
 1/0
except Exception as e:
 print(f&quot;{type(e).__name__} at line {e.__traceback__.tb_lineno} of {__file__}: {e}&quot;)
</code></pre>
Output:
<pre><code>ZeroDivisionError at line 48 of /Users/.../script.py: division by zero
</code></pre>

blocks|key|1229541|text|如果您想要这样做，可以使用assert语句来引发一行错误。这将帮助您编写可静态修复的代码，并及早检查错误。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1229542|assert+type(A)+is+type(""),+"requires+a+string"|code-block|syntax|javascript|1229543|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

One liner error raising can be done with assert statements if that's what you want to do. This will help you write statically fixable code and check errors early.

<pre><code>assert type(A) is type(""), "requires a string"
</code></pre>

blocks|key|1229741|text|我建议使用try-except语句。此外，日志异常不使用print语句，而是在记录器上记录带有级别错误的消息，我发现这比打印输出更有效。此方法只能从异常处理程序中调用，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1229742|import+logging

try:
++++*code+goes+here*
except+BaseException:
++++logging.exception("*Error+goes+here*")|code-block|syntax|javascript|1229743|如果您想了解有关日志记录和调试的更多信息，有关于this+python+page的很好的文档。|offset|length|1229744|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.python.org/3/library/logging.html^0|0|0|O|G|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

I would recommend using a try-except statement. Also, rather than using a print statement, a logging exception logs a message with level ERROR on the logger, which I find is more effective than a print output. This method should only be called from an exception handler, as it is here:
<pre><code>import logging

try:
 *code goes here*
except BaseException:
 logging.exception(&quot;*Error goes here*&quot;)
</code></pre>
There's good documentation on <a href="https://docs.python.org/3/library/logging.html" rel="nofollow noreferrer">this python page</a> if you want to learn more about logging and debugging.

blocks|key|1444721|text|#试试这个|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1444722|try:

++++print("Hare+Krishna!")

except+Exception+as+er:

++++print(er)|code-block|syntax|javascript|1444723|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

#Try this
<pre><code>try:

 print(&quot;Hare Krishna!&quot;)

except Exception as er:

 print(er)
 
</code></pre>

<pre><code>try:
 something here
except:
 print('the whatever error occurred.')
</code></pre>

How can I print the error/exception in my <code>except:</code> block?

How to print an exception in Python?

Python

try:    something hereexcept:    print('the whatever error occurred.')如何在except:块中打印错误/异常？

问如何在Python中打印异常？
EN

回答 9

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问如何在Python中打印异常？EN

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