This document discusses various string methods in Python including upper(), lower(), capitalize(), startswith(), endswith(), strip(), split(), and join(). It provides examples of how to use each method, such as converting strings to uppercase and lowercase, checking if a string starts or ends with certain text, stripping leading and trailing characters, and splitting or joining strings.

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Common String Methods
Pavan Verma
Python Programming Essentials
@YinYangPavan

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Common String Methods
 upper()
 lower()
 capitalize()
 startswith()
 endswith()
 strip()
 find()
 split()
 join()
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upper, lower, capitalize
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message = "enter the dragon"
print message.upper()
print message.lower()
print message.capitalize()
Outputs:
ENTER THE DRAGON
enter the dragon
Enter the dragon
upper(): Converts all
lowercase letters in string to
uppercase
lower(): Converts all
uppercase letters in string to
lowercase
capitalize():
Capitalizes first letter of
string

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startswith
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startswith(text)
• Checks whether the string starts with text
• Return’s True if there is a match otherwise False
>>> str = "explicit is better than implicit"
>>> str.startswith('explicit')
True
>>> str.startswith('Explicit')
False
>>>

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startswith (2)
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str.startswith(text, begin, end)
startswith()optionally takes two arguments begin and
end
• text − This is the string to be checked
• begin − This is the optional parameter to set start index of
the matching boundary
• end − This is the optional parameter to set start index of
the matching boundary

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startswith (3)
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str = "explicit is better than implicit“
>>> print str.startswith("is", 9)
True
>>> print str.startswith("better", 12, 18)
True
startswith()returns True if matching string found else
False

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endswith
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>>> str = "explicit is better than implicit"
>>> str.endswith("implicit")
True
>>> str.endswith("implicit", 20)
True
>>> str.endswith("implicit", 25)
False
>>> str.endswith("than", 19, 23)
True
endswith(text)works the same way as startswith difference
being it checks whether the string ends with text or not

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message = " enter the dragon "
print message.strip()
Output:
enter the dragon
message = "--enter the dragon--"
print message.strip(‘-’)
Output:
enter the dragon
strip(chars):
• returns a copy of the
string with leading and
trailing characters
removed
• If chars is omitted
or None, whitespace
characters are
removed
strip
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message = " enter the dragon "
message.lstrip()
Output:
'enter the dragon'
message = "--enter the dragon--"
message.lstrip('-')
Output:
'enter the dragon--'
lstrip(chars):
• returns a copy of the
string with leading
characters removed
• If chars is omitted
or None, whitespace
characters are
removed
lstrip
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message = " enter the dragon "
message.rstrip()
Output:
' enter the dragon'
message = "--enter the dragon--"
message.rstrip('-')
Output:
'--enter the dragon'
rstrip(chars):
• returns a copy of the
string with trailing
characters removed
• If chars is omitted
or None, whitespace
characters are
removed
rstrip
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SPLITTING AND JOINING
STRINGS

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Splitting
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message = "enter the dragon"
print message.split()
Output:
['enter', 'the', 'dragon']
split()returns a list of words of the string

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Splitting (2)
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message = "enter-the-dragon"
print message.split('-')
Output:
['enter', 'the', 'dragon']
split(delimiter)
delimiter: character or characters which we want to
use to split the string, by default it will be space

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Joining
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seq_list = ['enter', 'the', 'dragon']
print ''.join(seq_list)
Output:
enter the dragon
str.join()
returns a string in which the string elements of sequence have
been joined by str separator

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Joining (2)
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seq_tuple = ('enter','the','dragon')
print '-'.join(seq_tuple)
Output:
enter-the-dragon

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splitting/joining example
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Lets say you have a link
'foo.com/forum?filter=comments&num=20'
1. You have to separate out the querystring from
url
2. You have to then separate out key-value pairs in
querystring
3. Now update the filter to views and num to 15
and form the url again

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splitting/joining example (2)
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>>> link = 'foo.com/forum?filter=comments&num=20'
>>> components = link.split('?')
>>> components
['foo.com/forum', 'filter=comments&num=20']
>>> url = components[0]
>>> qs = components[1]
>>> url
'foo.com/forum'
>>> qs
'filter=comments&num=20'
Step 1
Split the link using '?' as
delimiter to separate out
url and querystring

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splitting/joining example (3)
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>>> qs
'filter=comments&num=20'
>>>params = qs.split('&')
>>> params
['filter=comments', 'num=20']
Step 2
Split the querystring
using '&' as delimiter

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splitting/joining example (4)
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>>> params
['filter=comments', 'num=20']
>>> params[0] = 'filter=views'
>>> params[1] = 'num=15'
>>> params
['filter=views', 'num=15']
>>> qs = '&'.join(params)
>>> qs
'filter=views&num=15'
Step 3
Update the parameters and
join them using '&' as
delimiter to form
querystring

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splitting/joining example (5)
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>>> url
'foo.com/forum'
>>> qs
'filter=views&num=15'
>>> '?'.join([url, qs])
'foo.com/forum?filter=views&num=15'
>>> link = '?'.join([url, qs])
>>> link
'foo.com/forum?filter=views&num=15'
Step 4
join url and querystring
using '?' as delimiter

21. Summary
 upper, lower, capitalize
 startswith and endswith
 strip, lstrip and rstrip
 splitting and joining strings
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Resources
 String methods python docs
http://docs.Python.org/2/library/stdtypes.html#string-
methods
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