Functions that process case-sensitive characters in a string
Contents
- 1. Function str.capitalize(). The first character of the string is capitalized
- 2. Function str.casefold(). Return the folded copy of the string
- 3. Function str.lower(). Character case conversion
- 4. Function str.swapcase(). Return a copy of a string with transformation of lowercase to uppercase characters
- 5. Function str.title(). Return the string with uppercase letters in words
- 6. Function str.upper(). Convert string characters to uppercase
- Related topics
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1. Function str.capitalize(). The first character of the string is capitalized
The capitalize() function returns a copy of the string with the first character in uppercase, and the other characters in lowercase.
Example.
# Function str.capitalize() # Only letters are accepted s1 = 'abcdef ghi' s2 = str.capitalize(s1) # s2 = 'Abcdef ghi' s1 = 't' s2 = str.capitalize(s1) # s2 = 'T' s1 = '234' s2 = str.capitalize(s1) # s2 = '234' s1 = 'ABCDEF GHI' s2 = str.capitalize(s1) # s2 = 'Abcdef ghi' # Accounting for the Cyrillic alphabet s1 = 'байт!' s2 = str.capitalize(s1) # s2 = '\xc1\xe0\xe9\xf2!'
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2. Function str.casefold(). Return the folded copy of the string
The str.casefold() function returns a minimized copy of the string. The concept of a “casefolded copy” of a string means that in such a copy all the differences in the case of characters in the string are removed. The peculiarity of a “casefolded” copy of a string is that the lower() function cannot be applied to some characters, and the casefold() function can. An example of such a character is the German character ‘ß’, which in the casefold() function is replaced with ss characters, unlike the lower() function.
The function has been introduced in Python since version 3.3.
Example.
# Function casefold() - returns a folded copy of the string # Use with strings containing uppercase and lowercase letters s1 = 'Abcdef Ghi' s2 = str.casefold(s1) # s2 = 'abcdef ghi' s3 = s1.casefold() # s3 = 'abcdef ghi' # use with uppercase strings s4 = 'ABCDEF SS' s5 = s4.casefold() # s5 = 'abcdef ss'
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3. Function str.lower(). Character case conversion
The str.lower() function converts characters to lowercase.
Example.
# Function str.lower() s1 = 'ABCD' s2 = s1.lower() # s2 = 'abcd' s2 = 'Hello World!'.lower() # s2 = 'hello world!'
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4. Function str.swapcase(). Return a copy of a string with transformation of lowercase to uppercase characters
The str.swapcase() function returns a copy of a string with uppercase letters converted to lowercase and, conversely, lowercase converted to uppercase. The general form of a function call is as follows:
s2 = s1.swapcase()
where
- s1 – the specified string to be converted
- s2 – the resulting string in which all uppercase characters are converted to lowercase, and all lowercase characters are converted to uppercase.
For this function, it cannot be stated that the following expression
s.swapcase().swapcase() == s
will always be executed.
Example.
# Function str.swapcase() s1 = 'Abcd' s2 = s1.swapcase() # s2 = 'aBCD' s1 = 'a+5+BC+D' s2 = str.swapcase(s1) # s2 = 'A+5+bc+d' s2 = 'hELLO WORLD'.swapcase() # s2 = 'Hello world' # For cyrillic s1 = 'wEB-SITE' s2 = s1.swapcase() # s2 = 'Web-site'
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5. Function str.title(). Return the string with uppercase letters in words
The str.title() function returns a string in which all words begin with a capital letter. Other characters in these words are lowercase. The general form of using the function is as follows:
s2 = s1.title()
where
- s1 – source string;
- s2 – the resulting string in which the correction of characters that are the beginning of words is implemented.
The function has one feature. The character ‘\” of the apostrophe forms the boundary of the word. In some cases this is undesirable. To avoid this drawback, you need to use regular expressions.
Example.
# Function str.title s1 = 'hello world!' # s2 = 'Hello World!' s2 = s1.title() s1 = 'HELLO WORLD!' s2 = str.title(s1) # s2 = 'Hello World!' # A separate case with the apostrophe symbol '\'' s1 = "I'm happy!" s2 = s1.swapcase() # s2 = 'i'M HAPPY!'
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6. Function str.upper(). Convert string characters to uppercase
The str.upper() function allows you to get a copy of the string in which all characters are in upper case. According to the Python documentation, the general form of the function is as follows:
s2 = s1.upper()
where
- s1 – source string;
- s2 – the resulting string is a copy in which the lowercase characters of the string s1 are replaced with uppercase characters.
Character conversion is performed only for uppercase characters. These are characters that are included in the following categories:
- “Lu” – Letter uppercase;
- “Ll” – Letter lowercase;
- “Lt” – Letter titlecase.
Example.
# Function str.upper() s1 = 'abcdef' s2 = s1.upper() # s2 = 'ABCDEF' s1 = '' # empty string s2 = str.upper(s1) # s2 = '' s1 = '5+6=11' s2 = s1.upper() # s2 = '5+6=11' s2 = 'aBc deFg'.upper() # s2 = 'ABC DEFG'
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Related topics
- Functions for working with string that determine the features of a string
- Functions based on searching and replacing a substring in a string
- Functions defining and processing the beginning and the end of a string
- Formatting styles. String processing functions according to format or encoding rule
- Functions of strings alignment
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