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Python String functions

In Python 3, there are many built-in functions for working with strings. Here are some of the most commonly used string functions:

  1. len(string): Returns the length of the string.

  2. str(object): Converts an object to a string representation.

  3. str.capitalize(): Returns a copy of the string with its first character capitalized and the rest in lowercase.

  4. str.upper(): Returns a copy of the string with all the characters in uppercase.

  5. str.lower(): Returns a copy of the string with all the characters in lowercase.

  6. str.strip(): Returns a copy of the string with leading and trailing whitespaces removed.

  7. str.replace(old, new): Returns a copy of the string with all occurrences of old replaced with new.

  8. str.split(sep): Returns a list of substrings separated by sep.

  9. str.join(iterable): Returns a string that concatenates the elements of iterable using the string as a separator.

  10. str.format(*args, **kwargs): Formats the string using the positional and keyword arguments.

  11. str.isdigit(): Returns True if all characters in the string are digits and False otherwise.

  12. str.isalpha(): Returns True if all characters in the string are alphabetic and False otherwise.

  13. str.islower(): Returns True if all characters in the string are in lowercase and False otherwise.

  14. str.isupper(): Returns True if all characters in the string are in uppercase and False otherwise.

These are just a few of the most commonly used string functions in Python 3. For a complete list, you can refer to the official Python documentation.

Lenght Of String

len() function is used to find the lenght of string. It returns the integer number.

str_ = "python programming"
print(len(str_))  # return 18

Slicing The String

slicing string means , extract the substring from string as given index and return new string.

syntax of slicing string str[start:end] end excluded.

str_ = "python programming"
print(str_[4:10])     # returns 'on pro'
print(str_[:])        # return 'python programming'
print(str_[:6])       # return 'python'
print(str_[-11:-4])   # returns 'program'

Count() Function In String

count() function count the given string and return the numbers of occurances in string and return integer number. count() function may takes three arguments str.count("string",start,end) 

str_ = "python Programming"
print(str_.count("o"))       # returns 2

Strings Split() Function

split() functions split the string at the occurance of given string and return the list.

str_ = "python Programming"
print(str_.split(" "))     # return ['python', 'Programming']

Strings Strip() Function

strip() function is used to remove extra spaces from string. it will remove all white space such as beggining of string.

str_ = "   python Programming is easy to learn."
print(str_.strip())     # return python Programming is easy to learn.

Strings Replace() Function

replace() function is used to replace the string in a string. It will replace all occurances.

str_ = "python Programming is easy to learn."
print(str_.replace("r","R"))     # return python PRogRamming is easy to leaRn.

String Upper() And Lower() Function

upper() function turn all the character uppercase and lower() function turn the all characters lowercase and return.

str_ = "python Programming"
print(str_.upper())     # returns PYTHON PROGRAMMING
print(str_.lower())        # returns python programming

String Capitalize() Function

capitalize() function change the first letter uppercase in string.

str_ = "hello world"
print(str_.capitalize())  # Hello world

String Casefold() Function

casefold() function change the letter to lowercase same as lower() function.

str_ = "Hello World "
print(str_.casefold())  # hello world

String Startswith() Function

startswith() function return True if the string is starting with specified value else return False.

str_ = "hello python\n programmer"
print(str_.startswith("python"))   # False
print(str_.startswith("hel"))      # True

String Endswith() Function

endswith() if string is endswith specific value it will return True else False. endswith() function may takes three arguments endswith("string",start,ends) 

str_ = "Hello World "
print(str_.endswith("ld"))  # False
str_ = "Hello World"
print(str_.endswith("ld"))  # True
print(str_.endswith("ld",6))  # True

String Find() Function

find() return the index of first occurance of value else return the -1 . it may take three arguments str.find("str",start, end) 

str_ = "Hello World "
print(str_.find("s"))  # -1
print(str_.find("o"))  # 4

String Format() Function

format() format the string with placeholder . we can specify the placeholder within this bracket {} here is the Example: 

str_ = "Hello World {python} "
print(str_.format(python="with python"))    # output - Hello World with python

String Index() Function

index() function return the index of first occurance value, if specified value was found in string else raise exception as "substring not found". this function may take upto three arguments str.index("str",start,end) 

str_ = "Hello World"
print(str_.index("W"))    # output - 6

String Isalnum() Function

isalnum() function return True is the all characters in a string are a-z or 0-9 or A-Z .

str_ = "hello world 5 time"
print(str_.isalnum())    # output - False
str_ = "helloWorld5time"
print(str_.isalnum())    # output - True

String Isalpha() Function

isalpha() function return True if all characters are alphabet in a string else false.

str_ = "hello time"
print(str_.isalpha())    # output - False
str_ = "helloWorld5time"
print(str_.isalpha())    # output - False
str_ = "helloWorldtime"
print(str_.isalpha())    # output - True

String Isascii() Function

isascii() function return True if all characters are belongs to ascii character sets.

str_ = "hello time"
print(str_.isascii())    # output - True
str_ = "helloWorl534$^$#5time"
print(str_.isascii())    # output - True
str_ = "{ helloWorldtime"
print(str_.isascii())    # output - True

String Isdecimal() Function

isdecimal() function return the True if all characters in a string are 0-9 else return False.

str_ = "3539 5"
print(str_.isdecimal())   # False
str_ = "8380033339"  
print(str_.isdecimal())   # True

String Isdigit() Function

isdigit() function return True if all characters in a string are digits else return False.

str_ = "3539 5"
print(str_.isdigit())   # False
str_ = "8380033339"  
print(str_.isdigit())   # True

String Checking As Identifiers Using Isidentifier()

isidentifier() function return True if string is valid identifiers else return False.

str_ = "HelloWorld"
print(str_.isidentifier())   # True
str_ = "Hello World"  
print(str_.isidentifier())   # False
str_ = "_Hello5World"  
print(str_.isidentifier())   # True

String Islower() Function

islower() function return True if all characters is a string are lowercase else return False.

str_ = "HelloWorld"
print(str_.islower())   # False
str_ = "hello world"  
print(str_.islower())   # True
str_ = "_hello5 world"  
print(str_.islower())   # True

String Isnumeric() Function

isnumeric() function return True if all characters is a string are 0-9 else return Fasle.

str_ = "398579387"
print(str_.isnumeric())   # True
str_ = "hello 835"  
print(str_.isnumeric())   # Fasle
str_ = "-9837"  
print(str_.isnumeric())   # Fasle
str_ = "98.37"  
print(str_.isnumeric())   # Fasle

String Isprintable() Function

isprintable() function return True if all characters are printable in a string else return False.

str_ = "3985\n79"
print(str_.isprintable())   # Fasle
str_ = "hello\t835"  
print(str_.isprintable())   # Fasle
str_ = "Hello World"  
print(str_.isprintable())   # True
str_ = "98.37"  
print(str_.isprintable())   # True

String Isupper() Function

isupper() function return True if all characters are in uppercase letter else return False.

print(isupper("Hello World"))

String Swapcase() Function

swapcase() function return the string after converting uppercase to the lowercase and lowercase to uppercase .

str_ = "Hello World"
print(str_.swapcase())   # hELLO wORLD
str_ = "hello"  
print(str_.swapcase())   # HELLO
str_ = "Hello World"  
print(str_.swapcase())   # hELLO wORLD

String Join() Function

join() function return the string after joining all the given iterable object.

str_ = ""
lst = ["hi", "I", "am", "developer"]
print(str_.join(lst))   # hiIamdeveloper

String Rfind() Function

rfind() function return the index of last occurance of given value . if not found in string return -1 .

str_ = "hello python programmer"
print(str_.rfind("o"))   # 15

String Rindex() Function

rindex() function return the index of last occurance of given value . if not found in raise error as "substring not found".

str_ = "hello python programmer"
print(str_.rindex("o"))   # 15

String Rsplit() Function

rsplit() function return a list after spliting by specified seperator with maximum . syntax is str.rsplit(seperator, maxsplit) 

str_ = "hello python programmer"
print(str_.rsplit(" "))   # ['hello', 'python', 'programmer']

String Splitlines() Function

splitlines() return the list after spliting by "\n" occurance in a string.

str_ = "hello python\n programmer"
print(str_.splitlines())   # ['hello python', ' programmer']

String Strip() Function

strip() function return the string after removing extra white space from start or end of string.

str_ = "  hello python   programmer  "
print(str_.strip())      # hello python   programmer

String Zfill() Function

zfill() function return the string after adding the zero at first upto given size.

str_ = "hello python programmer"
print(str_.zfill(40))      # 00000000000000000hello python programmer