Get all lowercase letters python

The lower[] method converts all uppercase characters in a string into lowercase characters and returns it.

Example

message = 'PYTHON IS FUN'

# convert message to lowercase
print[message.lower[]]

# Output: python is fun

Syntax of String lower[]

The syntax of lower[] method is:

string.lower[]

lower[] Parameters[]

lower[] method doesn't take any parameters.

lower[] Return value

lower[] method returns the lowercase string from the given string. It converts all uppercase characters to lowercase.

If no uppercase characters exist, it returns the original string.

Example 1: Convert a string to lowercase

# example string
string = "THIS SHOULD BE LOWERCASE!"
print[string.lower[]]

# string with numbers
# all alphabets should be lowercase
string = "Th!s Sh0uLd B3 L0w3rCas3!"
print[string.lower[]]

Output

this should be lowercase!
th!s sh0uld b3 l0w3rcas3!

Example 2: How lower[] is used in a program?

# first string
firstString = "PYTHON IS AWESOME!"

# second string
secondString = "PyThOn Is AwEsOmE!"

if[firstString.lower[] == secondString.lower[]]:
    print["The strings are same."]
else:
    print["The strings are not same."]

Output

The strings are same.

Note: If you want to convert to uppercase string, use upper[]. You can also use swapcase[] to swap between lowercase to uppercase.

I need to know if there is a function that detects the lowercase letters in a string. Say I started writing this program:

s = input['Type a word']

Would there be a function that lets me detect a lowercase letter within the string s? Possibly ending up with assigning those letters to a different variable, or just printing the lowercase letters or number of lowercase letters.

While those would be what I would like to do with it I'm most interested in how to detect the presence of lowercase letters. The simplest methods would be welcome.

asked Oct 17, 2012 at 13:04

4

To check if a character is lower case, use the islower method of str. This simple imperative program prints all the lowercase letters in your string:

for c in s:
    if c.islower[]:
         print c

Note that in Python 3 you should use print[c] instead of print c.

Possibly ending up with assigning those letters to a different variable.

To do this I would suggest using a list comprehension, though you may not have covered this yet in your course:

>>> s = 'abCd'
>>> lowercase_letters = [c for c in s if c.islower[]]
>>> print lowercase_letters
['a', 'b', 'd']

Or to get a string you can use ''.join with a generator:

>>> lowercase_letters = ''.join[c for c in s if c.islower[]]
>>> print lowercase_letters
'abd'

answered Oct 17, 2012 at 13:07

Mark ByersMark Byers

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0

There are 2 different ways you can look for lowercase characters:

1. Use str.islower[] to find lowercase characters. Combined with a list comprehension, you can gather all lowercase letters:

   lowercase = [c for c in s if c.islower[]]
   

2. You could use a regular expression:

   import re
   
   lc = re.compile['[a-z]+']
   lowercase = lc.findall[s]
   

The first method returns a list of individual characters, the second returns a list of character groups:

>>> import re
>>> lc = re.compile['[a-z]+']
>>> lc.findall['AbcDeif']
['bc', 'eif']

answered Oct 17, 2012 at 13:10

Martijn Pieters♦Martijn Pieters

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6

There are many methods to this, here are some of them:

1. Using the predefined str method islower[]:

   >>> c = 'a'
   >>> c.islower[]
   True
   

2. Using the ord[] function to check whether the ASCII code of the letter is in the range of the ASCII codes of the lowercase characters:

   >>> c = 'a'
   >>> ord[c] in range[97, 123]
   True
   

3. Checking if the letter is equal to it's lowercase form:

   >>> c = 'a'
   >>> c.lower[] == c
   True
   

4. Checking if the letter is in the list ascii_lowercase of the string module:

   >>> from string import ascii_lowercase
   >>> c = 'a'
   >>> c in ascii_lowercase
   True
   

But that may not be all, you can find your own ways if you don't like these ones: D.

Finally, let's start detecting:

d = str[input['enter a string : ']]
lowers = [c for c in d if c.islower[]]

# here i used islower[] because it's the shortest and most-reliable
# one [being a predefined function], using this list comprehension
# is [probably] the most efficient way of doing this

answered May 4, 2016 at 20:32

DjaouadNMDjaouadNM

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2

You should use raw_input to take a string input. then use islower method of str object.

s = raw_input['Type a word']
l = []
for c in s.strip[]:
    if c.islower[]:
        print c
        l.append[c]
print 'Total number of lowercase letters: %d'%[len[l] + 1]

Just do -

dir[s]

and you will find islower and other attributes of str

answered Oct 17, 2012 at 13:13

HussainHussain

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1

import re
s = raw_input['Type a word: ']
slower=''.join[re.findall[r'[a-z]',s]]
supper=''.join[re.findall[r'[A-Z]',s]]
print slower, supper

Prints:

Type a word: A Title of a Book
itleofaook ATB

Or you can use a list comprehension / generator expression:

slower=''.join[c for c in s if c.islower[]]
supper=''.join[c for c in s if c.isupper[]]
print slower, supper

Prints:

Type a word: A Title of a Book
itleofaook ATB

answered Oct 17, 2012 at 13:10

If you don't want to use the libraries and want simple answer then the code is given below:

  def swap_alpha[test_string]:
      new_string = ""
      for i in test_string:
          if i.upper[] in test_string:
              new_string += i.lower[]

          elif i.lower[]:
                new_string += i.upper[]

          else:
              return "invalid "

      return new_string


user_string = input["enter the string:"]
updated = swap_alpha[user_string]
print[updated]

answered Jun 14, 2020 at 12:47

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