String startswith, endswith ExamplesUse the startswith and endswith methods to test the beginning and end of strings.
This page was last reviewed on Jun 15, 2023.
Startswith, endswith. All Python strings have a start and an end. Often we need to test the starts and ends of strings. We use the startswith and endswith methods.
We can take a substring and compare that to a string—this can do the same thing as startswith or endswith. But with specialized methods, our code is clearer and likely faster.
Example. Here we have a string that has many characters in it. We want to see what prefixes and suffixes may match. We use several if-statements.
Step 1 We use startswith on an example string. We see that the string begins with the letters "cat."
Step 2 We test a longer prefix to the string. We can use any length of string as an argument to startswith.
Step 3 We use "not startswith" to see if the string does not start with "elephant."
Step 4 Here we use the endswith method. It uses the same syntax as startswith but tests the final characters in a string.
Step 5 If we want to see if something does not match, we can test against the False constant.
phrase = "cat, dog and bird" # Step 1: see if the phrase starts with this string. if phrase.startswith("cat"): print(True) # Step 2: a longer prefix. if phrase.startswith("cat, dog"): print(True) # Step 3: it does not start with this string. if not phrase.startswith("elephant"): print(False) # Step 4: test the end of the string. if phrase.endswith("bird"): print("Ends with bird") # Step 5: does not match. if phrase.endswith("?") == False: # Does not end in a question mark. print(False)
True True False Ends with bird False
Some notes, performance. In my performance testing, I have found Python tends to be fastest when the minimal number of statements and method calls are made.
And This means startswith and endswith are a good choice—they can keep program short and clear.
With string-testing methods like startswith and endswith, we can check the beginning and ends of strings. This can avoid complexity in code.
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Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
This page was last updated on Jun 15, 2023 (edit link).
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