Python String -Part 1

In python, strings can be created by enclosing the character or the sequence of characters in the quotes. Python allows us to use single quotes, double quotes, or triple quotes to create the string.

Python capitalize() method converts first character of the string into uppercase without altering the whole string. It changes the first character only and skips rest of the string unchanged.

Str = javatpoint

Print(“Old value: “, Str)

print(“New value: ”,Str.capitalize())

Old value: javatpoint

New value: Javatpoint

Python Casefold() method returns a lowercase copy of the string. It is more simillar to lowercase method except it revomes all case distinctions present in the string.
str = “JAVATPOINT”
# Calling function
str2 = str.casefold()
# Displaying result
print(“Old value:”, str)
print(“New value:”, str2)
Output:
Old value: JAVATPOINT
New value: javatpoint

Python center() method alligns string to the center by filling paddings left and right of the string. This method takes two parameters, first is a width and second is a fillchar which is optional. The fillchar is a character which is used to fill left and right padding of the string.
center(width[,fillchar])
str = “Hello Javatpoint” 

# Calling function 

print(len(str))

str2 = str.center(20) 

# Displaying result 

print(“Old value:”, str) 

print(“New value:”, str2)
Output
16
Old value: Hello Javatpoint
New value:   Hello Javatpoint

It returns the number of occurences of substring in the specified range. It takes three parameters, first is a substring, second a start index and third is last index of the range. Start and end both are optional whereas substring is required.
# Python count() function example 

# Variable declaration 

str = “Hello Javatpoint” 

str2 = str.count('t')

# Displaying result 

print(“occurences:”, str2)
Output:
occurences: 2

Python encode() method encodes the string according to the provided encoding standard. By default Python strings are in unicode form but can be encoded to other standards also.
Encoding is a process of converting text from one standard code to another.
# Python encode() function example
# Variable declaration
str = “HELLO”
encode = str.encode()
# Displaying result
print(“Old value”, str)
print(“Encoded value”, encode)
Output:
Old value HELLO
Encoded value b 'HELLO'

Python endswith() method returns true of the string ends with the specified substring, otherwise returns false.
endswith(suffix[, start[, end]]) 

# Python endswith() function example
# Variable declaration
str = “Hello this is javatpoint.”
isends = str.endswith(“is”,10)
# Displaying result
print(isends)
Output:
False

# Python endswith() function example
# Variable declaration
str = “Hello this is javatpoint.”
isends = str.endswith(“is”,0,13)
# Displaying result
print(isends)
Output:
True

Python expandstabs() method replaces all the characters by sepecified spaces. By default a single tab expands to 8 spaces which can be overridden according to the requirement.
We can pass 1, 2, 4 and more to the method which will replace tab by the these number of space characters.

# Python endswith() function example
# Variable declaration
str = “Welcome \t to \t the \t Javatpoint.”
# Calling function
str2 = str.expandtabs(1)
str3 = str.expandtabs(2)
str4 = str.expandtabs(4)
# Displaying result
print(str2)
print(str3)
print(str4) 

Output:

Welcome   to   the   Javatpoint.

Welcome    to    the   Javatpoint.

Welcome      to      the     Javatpoint.

Python find() method finds substring in the whole string and returns index of the first match. It returns -1 if substring does not match.

Syntax

find(sub[, start[, end]]) 

Parameters

sub : substring

start : start index a range

end : last index of the range

Return Type

If found it returns index of the substring, otherwise -1.

Python String find() Method Example

An example of simple find method which takes only single parameter (a substring).

# Python find() function example 

# Variable declaration 

str = “Welcome to the Javatpoint.” 

# Calling function 

str2 = str.find(“the”) 

# Displaying result 

print(str2) 

Output:

11

Python String find() Method Example

It returns -1 if not found any match, see the example.

# Python find() function example 

# Variable declaration 

str = “Welcome to the Javatpoint.” 

# Calling function 

str2 = str.find(“is”) 

# Displaying result 

print(str2) 

Output:

-1

Python String find() Method Example

# Python find() function example 

# Variable declaration 

str = “Welcome to the Javatpoint.” 

# Calling function 

str2 = str.find(“t”) 

str3 = str.find(“t”,20,25) 

# Displaying result 

print(str2) 

print(str3) 

Output:

8

24

Python format() method is used to perform format operations on string. While formatting string a delimiter {} (braces) is used to replace it with the value. This delimeter either can contain index or positional argument.

Syntax

format(*args, **kwargs) 

Parameters

*args : substring

**kwargs : start index a range

Return Type

It returns a formatted string.

Python String format() Method Example

The delimiter (braces) are using numerical index to replace and format string.

# Python format() function example 

# Variable declaration 

str = “Java” 

str2 = “C#” 

# Calling function 

str3 = “{1} and {0} both are programming languages”.format(str,str2) 

# Displaying result 

print(str3) 

Output:

C# and Java both are programming languages

Python index() method is same as the find() method except it returns error on failure. This method returns index of first occurred substring and an error if there is no match found.

Syntax

index(sub[, start[, end]]) 

Parameters

sub : substring

start : start index a range

end : last index of the range

Return Type

If found it returns an index of the substring, otherwise an error ValueError.

Python String index() Method Example

# Python index() function example 

# Variable declaration 

str = “Welcome to the Javatpoint.” 

# Calling function 

str2 = str.index(“at”) 

# Displaying result 

print(str2) 

Output:

18

Python String index() Method Example

An error is thrown if the substring is not found.

# Python index() function example 

# Variable declaration 

str = “Welcome to the Javatpoint.” 

# Calling function 

str2 = str.index(“ate”) 

# Displaying result 

print(str2) 

Output:

ValueError: substring not found

Python String index() Method Example

We can also pass start and end index as parameters to make process more customized.

# Python index() function example 

# Variable declaration 

str = “Welcome to the Javatpoint.” 

# Calling function 

str2 = str.index(“p”,19,21) 

# Displaying result 

print(“p is present at :”,str2,”index”) 

Output:

p is present at : 20 index

Python isalnum() method checks whether the all characters of the string is alphanumeric or not. A character which is either a letter or a number is known as alphanumeric. It does not allow special chars even spaces.

Syntax

isalnum() 

Parameters

No parameter is required.

Return

It returns either True or False.

Python String isalnum() Method Example

If there is a space anywhere in the string, it returns False. See the example below.

# Python isalnum() function example 

# Variable declaration 

str = “Welcome123” # True 

str3 = “Welcome 123” # False 

# Calling function 

str2 = str.isalnum() 

str4 = str3.isalnum() 

# Displaying result 

print(str2) 

print(str4) 

Output:

True

False

Python isalpha() method returns true if all characters in the string are alphabetic. It returns False if the characters are not alphabetic. It returns either True or False.

Syntax

isalpha() 

Parameters

No parameter is required.

Return

It returns either True or False.

Python String isalpha() Method Example

# Python isalpha() method example 

# Variable declaration 

str = “Javatpoint” 

if str.isalpha() == True: 

    print(“String contains alphabets”) 

else: print(“Stringn contains other chars too.”) 

Output:

String contains alphabets

Python isdecimal() method checks whether all the characters in the string are decimal or not. Decimal characters are those have base 10.

This method returns boolean either true or false.

Syntax

isdecimal() 

Parameters

No parameter is required.

Return

It returns either True or False.

Python String isdecimal() Method Example

A simple example of isdecimal() method to check whether the string contains decimal value.

# Python isdecimal() method example 

# Variable declaration 

str = “Javatpoint” 

# Calling function 

str2 = str.isdecimal() 

# Displaying result 

print(str2) 

Output:

False

Python isdigit() method returns True if all the characters in the string are digits. It returns False if no character is digit in the string.

Syntax

isdigit() 

Parameters

No parameter is required.

Return

It returns either True or False.

Python String isdigit() Method Example

It returns true only if all the characters are digit. See the example below.

# Python isdigit() method example 

# Variable declaration 

str = “12345” 

str3 = “120-2569-854” 

# Calling function 

str2 = str.isdigit() 

str4 = str3.isdigit() 

# Displaying result 

print(str2) 

print(str4) 

Output:

True

False

Python isidentifier() method is used to check whether a string is a valid identifier or not. It returns True if the string is a valid identifier otherwise returns False.

Python language has own identifier definition which is used by this method.

Syntax

isidentifier() 

Parameters

No parameter is required.

Return

It returns either True or False.

Python String isidentifier() Method Example

Here, we have created variety of identifiers. Some returns True and some False. See the example below.

# Python isidentifier() method example 

# Variable declaration 

str = “abcdef” 

str2 = “20xyz” 

str3 = “$abra” 

# Calling function 

str4 = str.isidentifier() 

str5 = str2.isidentifier() 

str6 = str3.isidentifier() 

# Displaying result 

print(str4) 

print(str5) 

print(str6) 

Output:

True

False

False

Python string islower() method returns True if all characters in the string are in lowercase. It returns False if not in lowercase.

Syntax

islower() 

Parameters

No parameter is required.

Return

It returns either True or False.

Python String islower() Method Example

A simple example to understand how to apply this method. It returns true, see the example below.

# Python islower() method example 

# Variable declaration 

str = “javatpoint” 

# Calling function 

str2 = str.islower() 

# Displaying result 

print(str2) 

Output:

True

Python isnumeric() method checks whether all the characters of the string are numeric characters or not. It returns True if all the characters are true, otherwise returns False.

Numeric characters include digit characters and all the characters which have the Unicode numeric value property.

Syntax

isnumeric() 

Parameters

No parameter is required.

Return

It returns either True or False.

Python String isnumeric() Method Example

See a senario where and how we can apply isnumeric() method in python programming

# Python isnumeric() method example 

str = “123452500” # True 

if str.isnumeric() == True: 

    print(“Numeric”) 

else: 

    print(“Not numeric”) 

str2 = “123-4525-00” # False 

if str2.isnumeric() == True: 

    print(“Numeric”) 

else: 

    print(“Not numeric”) 

Output:

Numeric

Not numeric

Python isprintable() method returns True if all characters in the string are printable or the string is empty. It returns False if any character in the string is Nonprintable.

Syntax

isprintable() 

Parameters

No parameter is required.

Return

It returns either True or False.

Python String isprintable() Method Example

Here, we are using some other characters like newline and tabs in the string. See the results of the example.

# Python isprintable() method example 

# Variable declaration 

str = “Hello, Javatpoint” 

str2 = “Learn Java here\n” 

str3 = “\t Python is a programming language” 

# Calling function 

str4 = str.isprintable() 

str5 = str2.isprintable() 

str6 = str3.isprintable() 

# Displaying result 

print(str4) 

print(str5) 

print(str6) 

Output:

True

False

False

Python isupper() method returns True if all characters in the string are in uppercase. It returns False if characters are not in uppercase.

Syntax

isupper() 

Parameters

No parameter is required.

Return

It returns either True or False.

Python String isupper() Method Example

# Python isupper() method example 

# Variable declaration 

str = “WELCOME TO JAVATPOINT” 

# Calling function 

str2 = str.isupper() 

# Displaying result 

print(str2) 

Output:

True

Python isspace() method is used to check space in the string. It returna true if there are only whitespace characters in the string. Otherwise it returns false. Space, newline, and tabs etc are known as whitespace characters and are defined in the Unicode character database as Other or Separator.

Syntax

isspace() 

Parameters

No parameter is required.

Return

It returns either True or False.

Python String isspace() Method Example

isspace() method returns true for all whitespaces like:

' ' - Space

'\t' - Horizontal tab

'\n' - Newline

'\v' - Vertical tab

'\f' - Feed

'\r' - Carriage return

# Python isspace() method example 

# Variable declaration 

str = “ “ # string contains space 

if str.isspace() == True: 

    print(“It contains space”) 

else: 

    print(“Not space”) 

str = “ab cd ef \n” 

if str.isspace() == True: 

    print(“It contains space”) 

else: 

    print(“Not space”) 

str = “\t \r \n” 

if str.isspace() == True: 

    print(“It contains space”) 

else: 

    print(“Not space”) 

Output:

It contains space

Not space

It contains space

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