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Mahmoud EL-kariouny
Mahmoud EL-kariouny

Posted on • Updated on

Python string methods explanation 🐍⛓️

#python #tutorial #beginners #programming

String methods

capitalize()

  • method returns a string where the first character is upper case
  • and the rest is lower case. 
txt = "hello world"

x = txt.capitalize()

# output
Hello world
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casefold()

  • method returns a string where all the characters are lower case.
  • This method is similar to the lower() method, but the casefold() method is stronger, more aggressive, meaning that it will convert more characters into lower case
  • and will find more matches when comparing two strings and both are converted using the casefold() method. 
txt = "Hello, And Welcome!"

x = txt.casefold()

# output
hello, and welcome!
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center()

  • method will center align the string, using a specified character (space is default) as the fill character. 
txt = "welcome"

x = txt.center(20, "*")

# output
   welcome  
******welcome*******
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count()

  • method returns the number of times a specified value appears in the string. 
txt = "hello, and welcome and hi! "

x = txt.count("and")

# output
2
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endswith()

  • method returns True if the string ends with the specified value, otherwise False. 
txt = "hello world!"

x = txt.endswith("!")

# output
True
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find()

  • method finds the first occurrence of the specified value.
  • method returns -1 if the value is not found.
  • Note:
  • The find() method is almost the same as the index() method,
  • the only difference is that the index() method raises an exception if the value is not found. 
txt = "Hello, welcome to python string."

x = txt.find('welcome')

# output
7
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format()

  • method formats the specified value(s) and insert them inside the string's placeholder.
  • The placeholder is defined using curly brackets: {}. 
txt1 = "Hello, {} to python {}".format("welcome", "string")

txt2 = "Hello, I'm {name} and I'm a {job}".format(name="Mahmoud", job="developer")

txt3 = "My name is {0}, I'm {1}".format("John",36)

# output
1 - Hello, welcome to python string
2 - Hello, I'm Mahmoud and I'm a developer
3 - My name is John, I'm 36
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format_map()

  • method is an inbuilt function in Python.
  • which is used to return a dictionary key’s value. 
details = {
    "name": "John",
    "job": "developer"
}

x = "Hi, I'm {name} and I'm a {job}. ".format_map(details)

# output
Hi, I'm John and I'm a developer.
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index()

  • method finds the first occurrence of the specified value.

  • The index() method raises an exception if the value is not found.

  • Note:

  • The index() method is almost the same as the find() method

  • The only difference is that the find() method returns -1 if the value is not found.

txt = "hello world!"

x = txt.index("!")

# output
11
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isalnum()

  • method returns True if all the characters are alphanumeric.
  • meaning alphabet letter (a-z) and numbers (0-9). 
txt = "Company12"

x = txt.isalnum()

# output
True
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isalpha()

  • method returns True if all the characters are alphabet letters (a-z).
  • Example of characters that are not alphabet letters: (space)!#%&? etc. 
txt = "helloworld"

x = txt.isalpha()

# output
True
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isdigit()

  • method returns True if all the characters are digits, otherwise False. 
txt = "2022"

x = txt.isdigit()

# output
True
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isidentifier()

  • method returns True if the string is a valid identifier, otherwise False.
  • A string is considered a valid identifier if it only contains alphanumeric letters (a-z) and (0-9), or underscores (_).
  • A valid identifier cannot start with a number, or contain any spaces. 
txt = "Python"

x = txt.isidentifier()

# output
True
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islower()

  • method returns True if all the characters are in lower case, otherwise False.
  • Numbers, symbols and spaces are not checked, only alphabet characters. 
txt = "hello world"

x = txt.islower()

# output
True
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lstrip()

  • method removes any leading characters (space is the default leading character to remove) 
txt = "     Python      "

x = txt.lstrip()

# output
Welcome to Python       methods explanation
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maketrans()

  • method returns a mapping table that can be used with the translate() method to replace specified characters. 
txt = "Delcome to Python"

trans = txt.maketrans("D", "W")

result = txt.translate(trans)

# output
Welcome to Python
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partition()

  • method searches for a specified string, and splits the string into a tuple containing three elements.
    1- The first element contains the part before the specified string.
    2- The second element contains the specified string.
    3- The third element contains the part after the string.

  • Note: This method searches for the first occurrence of the specified string.

txt = "welcome to python methods explanation"

x = txt.partition("python")

# output
('welcome to ', 'python', ' methods explanation')
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replace()

  • method replaces a specified phrase with another specified phrase.
  • Note: All occurrences of the specified phrase will be replaced
  • if nothing else is specified. 
txt = "welcome to python method explanation"

x = txt.replace("python", "replace()")

# output
welcome to replace() method explanation
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rfind()

  • method finds the last occurrence of the specified value.
  • method returns -1 if the value is not found. 
txt = "welcome to python method explanation"

x = txt.rfind("explanation")

# output
25
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rjust()

  • method will right align the string, using a specified character (space is default) as the fill character. 
txt = "hello world"

x = txt.rjust(20)

# output
          hello world
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split()

  • method splits a string into a list.
  • You can specify the separator, default separator is any whitespace. 
txt = "hello world"

x = txt.split()

# output
['hello', 'world']
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splitlines()

  • method splits a string into a list. The splitting is done at line breaks. 
txt = "welcome to python\n method explanation"

x = txt.splitlines()

# output
['welcome to python', ' method explanation']
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startswith()

  • method returns True if the string starts with the specified value, otherwise False. 
txt = "Hello world"

x = txt.startswith("Hello")

# output
True
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strip()

  • method removes any leading (spaces at the beginning) and trailing
  • (spaces at the end) characters (space is the default leading character to remove) 
txt = "    python      "

x = txt.strip()

# output
welcome to python method explanation
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swapcase()

  • method returns a string where all the upper case letters are lower case and vice versa. 
txt = "Hello My Name Is MAHMOUD"

x = txt.swapcase()

# output
hELLO mY nAME iS mahmoud
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title()

  • method returns a string where the first character in every word is upper case. Like a header, or a title.
  • If the word contains a number or a symbol, the first letter after that will be converted to upper case. 
txt = "python method explanation"

x = txt.title()

# output
Python Method Explanation
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upper()

  • method returns a string where all characters are in upper case.
  • Symbols and Numbers are ignored. 
txt = "Hello my friends"

x = txt.upper()


# output
HELLO MY FRIENDS
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zfill()

  • method adds zeros (0) at the beginning of the string, until it reaches the specified length.
  • If the value of the len parameter is less than the length of the string, no filling is done. 
txt = "50"

x = txt.zfill(10)

# output
0000000050
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Note:

  • All string methods returns new values.
  • They do not change the original string.

All the best to you.

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