Hướng dẫn startswith in list python

I'm trying to avoid using so many if statements and comparisons and simply use a list, but not sure how to use it with str.startswith:

if link.lower().startswith("js/") or link.lower().startswith("catalog/") or link.lower().startswith("script/") or link.lower().startswith("scripts/") or link.lower().startswith("katalog/"):
    # then "do something"

What I would like it to be is:

if link.lower().startswith() in ["js","catalog","script","scripts","katalog"]:
    # then "do something"

Any help would be appreciated.

asked Dec 9, 2013 at 2:00

2

str.startswith allows you to supply a tuple of strings to test for:

if link.lower().startswith(("js", "catalog", "script", "katalog")):

From the docs:

str.startswith(prefix[, start[, end]])

Return True if string starts with the prefix, otherwise return False. prefix can also be a tuple of prefixes to look for.

Below is a demonstration:

>>> "abcde".startswith(("xyz", "abc"))
True
>>> prefixes = ["xyz", "abc"]
>>> "abcde".startswith(tuple(prefixes)) # You must use a tuple though
True
>>>

answered Dec 9, 2013 at 2:01

6

You can also use any(), map() like so:

if any(map(l.startswith, x)):
    pass # Do something

Or alternatively, using a generator expression:

if any(l.startswith(s) for s in x)
    pass # Do something

answered Dec 9, 2013 at 2:57

4

str.startswith(str, begin=0,end=len(string));

str1 = "Vi du ham Python startswith"
print (str1.startswith('Vi'))
print (str1.startswith('du', 2, 4))
print (str1.startswith('Py', 2, 4))

str.startswith(str, begin=0,end=len(string));

str1 = "Vi du ham Python startswith"
print (str1.startswith('Vi'))
print (str1.startswith('du', 2, 4))
print (str1.startswith('Py', 2, 4))

In this tutorial, we will learn about the Python String startswith() method with the help of examples.

The startswith() method returns True if a string starts with the specified prefix(string). If not, it returns False.

Example

message = 'Python is fun'

# check if the message starts with Python
print(message.startswith('Python'))

# Output: True

Syntax of String startswith()

The syntax of startswith() is:

str.startswith(prefix[, start[, end]])

startswith() Parameters

startswith() method takes a maximum of three parameters:

• prefix - String or tuple of strings to be checked
• start (optional) - Beginning position where prefix is to be checked within the string.
• end (optional) - Ending position where prefix is to be checked within the string.

startswith() Return Value

startswith() method returns a boolean.

• It returns True if the string starts with the specified prefix.
• It returns False if the string doesn't start with the specified prefix.

Example 1: startswith() Without start and end Parameters

text = "Python is easy to learn."

result = text.startswith('is easy')
# returns False
print(result)

result = text.startswith('Python is ')
# returns True
print(result)

result = text.startswith('Python is easy to learn.')




# returns True
print(result)

Output

False
True
True

Example 2: startswith() With start and end Parameters

text = "Python programming is easy."

# start parameter: 7
# 'programming is easy.' string is searched
result = text.startswith('programming is', 7)
print(result)

# start: 7, end: 18
# 'programming' string is searched
result = text.startswith('programming is', 7, 18)
print(result)

result = text.startswith('program', 7, 18)
print(result)

Output

True
False
True

Passing Tuple to startswith()

It's possible to pass a tuple of prefixes to the startswith() method in Python.

If the string starts with any item of the tuple, startswith() returns True. If not, it returns False

Example 3: startswith() With Tuple Prefix

text = "programming is easy"
result = text.startswith(('python', 'programming'))

# prints True
print(result)

result = text.startswith(('is', 'easy', 'java'))

# prints False
print(result)

# With start and end parameter
# 'is easy' string is checked
result = text.startswith(('programming', 'easy'), 12, 19)

# prints False
print(result)

Output

True
False
False

If you need to check if a string ends with the specified suffix, you can use endswith() method in Python.

Description

Python string method startswith() checks whether string starts with str, optionally restricting the matching with the given indices start and end.

Syntax

Following is the syntax for startswith() method −

str.startswith(str, beg=0,end=len(string));

Parameters

• str − This is the string to be checked.

• beg − This is the optional parameter to set start index of the matching boundary.

• end − This is the optional parameter to end start index of the matching boundary.

Return Value

This method returns true if found matching string otherwise false.

Example

The following example shows the usage of startswith() method.

#!/usr/bin/python

str = "this is string example....wow!!!";
print str.startswith( 'this' )
print str.startswith( 'is', 2, 4 )
print str.startswith( 'this', 2, 4 )

When we run above program, it produces following result −

True
True
False

python_strings.htm