{"id":121071,"date":"2020-11-23T11:12:49","date_gmt":"2020-11-23T11:12:49","guid":{"rendered":"https:\/\/blog.finxter.com\/?p=17194"},"modified":"2020-11-23T11:12:49","modified_gmt":"2020-11-23T11:12:49","slug":"how-to-catch-and-print-exception-messages-in-python","status":"publish","type":"post","link":"https:\/\/sickgaming.net\/blog\/2020\/11\/23\/how-to-catch-and-print-exception-messages-in-python\/","title":{"rendered":"How to Catch and Print Exception Messages in Python"},"content":{"rendered":"

Python comes with an extensive support of exceptions and exception handling. An exception event interrupts and, if uncaught, immediately terminates a running program. The most popular examples are the IndexError<\/code><\/a>, ValueError<\/code><\/a>, and TypeError<\/a><\/code>. <\/p>\n

An exception will immediately terminate your program. To avoid this, you can catch the exception<\/strong> with a try\/except<\/code> block around the code where you expect that a certain exception may occur. Here’s how you catch and print a given exception:<\/strong><\/p>\n

To catch and print an exception that occurred in a code snippet, wrap it in an indented try<\/code> block, followed by the command \"except Exception as e\"<\/code> that catches the exception and saves its error message in string variable e<\/code>. You can now print the error message with \"print(e)\"<\/code> or use it for further processing.<\/p>\n

try: # ... YOUR CODE HERE ... #\nexcept Exception as e: # ... PRINT THE ERROR MESSAGE ... # print(e)\n<\/pre>\n
Example 1: Catch and Print IndexError<\/h2>\n
If you try to access the list element with index 100 but your lists consist only of three elements, Python will throw an IndexError<\/code> telling you that the list index is out of range<\/a>.<\/p>\n
try: lst = ['Alice', 'Bob', 'Carl'] print(lst[3])\nexcept Exception as e: print(e) print('Am I executed?')\n<\/pre>\n
Your genius code attempts to access the fourth element in your list with index 3—that doesn’t exist!<\/p>\n
\"\"<\/figure>\n
Fortunately, you wrapped the code in a try\/catch<\/code> block and printed the exception. The program is not terminated. Thus, it executes the final print()<\/a><\/code> statement after the exception has been caught and handled. This is the output of the previous code snippet.<\/p>\n
list index out of range\nAm I executed?<\/pre>\n
Example 2: Catch and Print ValueError<\/h2>\n
The ValueError<\/code><\/a> arises if you try to use wrong values in some functions. Here’s an example where the ValueError<\/code> is raised because you tried to calculate the square root of a negative number:<\/p>\n
import math try: a = math.sqrt(-2)\nexcept Exception as e: print(e) print('Am I executed?')<\/pre>\n
The output shows that not only the error message but also the string 'Am I executed?'<\/code> is printed.<\/p>\n
math domain error\nAm I executed?<\/pre>\n
Example 3: Catch and Print TypeError<\/h2>\n
Python throws the TypeError <\/a>object is not subscriptable<\/code> if you use indexing with the square bracket notation on an object that is not indexable. This is the case if the object doesn\u2019t define the __getitem__()<\/code> method. Here’s how you can catch the error and print it to your shell:<\/p>\n
try: variable = None print(variable[0])\nexcept Exception as e: print(e) print('Am I executed?')\n<\/pre>\n
The output shows that not only the error message but also the string 'Am I executed?'<\/code> is printed.<\/p>\n
'NoneType' object is not subscriptable\nAm I executed?<\/pre>\n
I hope you’re now able to catch and print your error messages. <\/p>\n
Summary<\/h2>\n
To catch and print an exception that occurred in a code snippet, wrap it in an indented try<\/code> block, followed by the command \"except Exception as e\"<\/code> that catches the exception and saves its error message in string variable e<\/code>. You can now print the error message with \"print(e)\"<\/code> or use it for further processing.<\/p>\n
Where to Go From Here?<\/h2>\n
Enough theory, let\u2019s get some practice!<\/p>\n
To become successful in coding, you need to get out there and solve real problems for real people. That\u2019s how you can become a six-figure earner easily. And that\u2019s how you polish the skills you really need in practice. After all, what\u2019s the use of learning theory that nobody ever needs?<\/p>\n
Practice projects is how you sharpen your saw in coding!<\/strong><\/p>\n
Do you want to become a code master by focusing on practical code projects that actually earn you money and solve problems for people?<\/p>\n
Then become a Python freelance developer! It\u2019s the best way of approaching the task of improving your Python skills\u2014even if you are a complete beginner.<\/p>\n
Join my free webinar \u201cHow to Build Your High-Income Skill Python\u201d<\/a> and watch how I grew my coding business online and how you can, too\u2014from the comfort of your own home.<\/p>\n
Join the free webinar now!<\/a><\/p>\n<\/p>\n
The post How to Catch and Print Exception Messages in Python<\/a> first appeared on Finxter<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"
Python comes with an extensive support of exceptions and exception handling. An exception event interrupts and, if uncaught, immediately terminates a running program. The most popular examples are the IndexError, ValueError, and TypeError. An exception will immediately terminate your program. To avoid this, you can catch the exception with a try\/except block around the code […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[857],"tags":[73,468,528],"class_list":["post-121071","post","type-post","status-publish","format-standard","hentry","category-python-tut","tag-programming","tag-python","tag-tutorial"],"_links":{"self":[{"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/posts\/121071","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/comments?post=121071"}],"version-history":[{"count":0,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/posts\/121071\/revisions"}],"wp:attachment":[{"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/media?parent=121071"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/categories?post=121071"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/tags?post=121071"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}