String Functions in Python - II | count, find, index, isalpha, isdigit and isalnum
Python String count() Method
Definition
and Usage
The count() method returns the number of times a
specified value appears in the string.
Syntax
string.count(value, start,
end)
Parameter
Values
|
Parameter |
Description |
|
value |
Required. A String. The string to value to search for |
|
start |
Optional. An Integer. The position to start the search.
Default is 0 |
|
end |
Optional. An Integer. The position to end the search.
Default is the end of the string |
Example
Return the number of times the value "e" appears in the
string:
a = "Hello, and welcome to my Channel"
x = a.count("e")
print(x)
or
x = "Hello,
and welcome to my Channel"
print(x.count(‘e’))
Output : 4
Example
Search from position 3:
a = "Hello, and welcome to my Channel"
x = a.count("e", 3)
print(x)
or
x = "Hello,
and welcome to my Channel"
print(x.count(‘e’,3))
Python
String find() Method
Definition
and Usage
The find() method finds the first occurrence of
the specified value.
The find() method returns -1 if the value is not
found.
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. (See example below)
Syntax
string.find(value, start,
end)
Parameter
Values
|
Parameter |
Description |
|
value |
Required. The value to search for |
|
start |
Optional. Where to start the search. Default is 0 |
|
end |
Optional. Where to end the search. Default is to the end of the
string |
Example
Where in the text is the word "welcome"?:
txt = "Hello, welcome to my Channel."
x = txt.find("welcome")
print(x)
Example
Where in the text is the first occurrence of the letter
"e"?:
txt = "Hello, welcome to my Channel."
x = txt.find("e")
print(x)
Example
Where in the text is the first occurrence of the letter
"e" when you only search between position 5 and 10?:
txt = "Hello, welcome to my Channel."
x = txt.find("e", 5, 10)
print(x)
Example
If the value is not found, the find() method returns -1, but the
index() method will raise an exception:
txt = "Hello, welcome to my world."
print(txt.find("x"))
print(txt.index("x"))
Python
String index() Method
Definition
and Usage
The index() method finds the first occurrence of
the specified value.
The index() method raises an exception if the value
is not found.
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. (See example below)
Syntax
string.index(value, start,
end)
Parameter
Values
|
Parameter |
Description |
|
value |
Required. The value to search for |
|
start |
Optional. Where to start the search. Default is 0 |
|
end |
Optional. Where to end the search. Default is to the end of the
string |
Example
Where in the text is the word "welcome"?:
y = "Hello, welcome to my Channel."
x = y.index("welcome")
print(x)
Example
Where in the text is the first occurrence of the letter
"e"?:
a = "Hello, welcome to my Channel."
x = a.index("e")
print(x)
Example
Where in the text is the first occurrence of the letter
"e" when you only search between position 5 and 10?:
a = "Hello, welcome to my channel."
x = a.index("e", 5, 10)
print(x)
Example
If the value is not found, the find() method returns -1, but the
index() method will raise an exception:
a = "Hello, welcome to my channel."
print(a.find("z"))
print(a.index("z"))
Python
String isalpha() Method
Definition
and Usage
The isalpha() method returns True if all the
characters are alphabet letters (a-z) otherwise returns False.
Example of characters that are not alphabet letters:
(space)!#%&? etc.
Syntax
string.isalpha()
Parameter
Values
No parameters.
Example
Check if all the characters in the text are letters:
a = "Computer"
x = a.isalpha()
print(x)
Or
a = "Computer"
print(a.isalpha())
Output : True
Example
Check if all the characters in the text is alphabetic:
a = "Computer10"
x = a.isalpha()
print(x)
Or
a = "Computer10"
print(a.isalpha())
Output : False
Python
String isdigit() Method
Definition
and Usage
The isdigit() method returns True if all the
characters are digits, otherwise False.
Exponents, like ², are also considered to be a digit.
Syntax
string.isdigit()
Parameter
Values
No parameters.
Example
Check if all the characters in the text are digits:
a = "12345"
x = a.isdigit()
print(x)
Or
a = "12345"
print(a.isdidit())
Output : Ture
Example
Check if all the characters in the text are digits:
a = "\u0030" #unicode for 0
b = "\u00B2" #unicode for ²
print(a.isdigit())
print(b.isdigit())
Output : Ture
Output : Ture
Example
Check if all the characters in the text are digits:
a = "12345ab"
x = a.isdigit()
print(x)
Or
a = "12345ab"
print(a.isdidit())
Output : False
Python
String isalnum() Method
Definition
and Usage
The isalnum() method returns True if all the
characters are alphanumeric, meaning alphabet letter (a-z) and numbers (0-9) otherwise
False.
Example of characters that are not alphanumeric: (space)!#%&?
etc.
Syntax
string.isalnum()
Parameter
Values
No parameters.
Example
Check if all the characters in the text are alphanumeric:
a = "Company12"
x = a.isalnum()
print(x)
Or
a = "Company12"
print(a.isalnum())
Output : True
Example
Check if all the characters in the text is alphanumeric:
a = "Company 12"
x = a.isalnum()
print(x)
Or
a = "Company
12"
print(a.isalnum())
Output : False
Method | Description |
capitalize() | Converts the first character to upper case |
casefold() | Converts string into lower case |
center() | Returns a centered string |
count() | Returns the number of times a specified value occurs in a string |
encode() | Returns an encoded version of the string |
endswith() | Returns true if the string ends with the specified value |
expandtabs() | Sets the tab size of the string |
find() | Searches the string for a specified value and returns the position of where it was found |
format() | Formats specified values in a string |
format_map() | Formats specified values in a string |
index() | Searches the string for a specified value and returns the position of where it was found |
isalnum() | Returns True if all characters in the string are alphanumeric |
isalpha() | Returns True if all characters in the string are in the alphabet |
isascii() | Returns True if all characters in the string are ascii characters |
isdecimal() | Returns True if all characters in the string are decimals |
isdigit() | Returns True if all characters in the string are digits |
isidentifier() | Returns True if the string is an identifier |
islower() | Returns True if all characters in the string are lower case |
isnumeric() | Returns True if all characters in the string are numeric |
isprintable() | Returns True if all characters in the string are printable |
isspace() | Returns True if all characters in the string are whitespaces |
istitle() | Returns True if the string follows the rules of a title |
isupper() | Returns True if all characters in the string are upper case |
join() | Converts the elements of an iterable into a string |
ljust() | Returns a left justified version of the string |
lower() | Converts a string into lower case |
lstrip() | Returns a left trim version of the string |
maketrans() | Returns a translation table to be used in translations |
partition() | Returns a tuple where the string is parted into three parts |
replace() | Returns a string where a specified value is replaced with a specified value |
rfind() | Searches the string for a specified value and returns the last position of where it was found |
rindex() | Searches the string for a specified value and returns the last position of where it was found |
rjust() | Returns a right justified version of the string |
rpartition() | Returns a tuple where the string is parted into three parts |
rsplit() | Splits the string at the specified separator, and returns a list |
rstrip() | Returns a right trim version of the string |
split() | Splits the string at the specified separator, and returns a list |
splitlines() | Splits the string at line breaks and returns a list |
startswith() | Returns true if the string starts with the specified value |
strip() | Returns a trimmed version of the string |
swapcase() | Swaps cases, lower case becomes upper case and vice versa |
title() | Converts the first character of each word to upper case |
translate() | Returns a translated string |
upper() | Converts a string into upper case |
zfill() | Fills the string with a specified number of 0 values at the beginning |
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