String Data Type of Python
String Data type :
It is a sequence of characters which is enclosed inside a double quotes or single quotes & triple quotes.
Properties of string data type :
- String can have any single or a sequence of character { [0–9] , [A-Z, a-z], [Special symbol] }.
2. Strings are immutable. (Once you create the data of string no change is possible ).
- You cannot add a new character and delete , replace any existing character.
3. Inside the string each and every character or element will have an Index Value = > Address .
- For every character or element having two index value.
- Positive index value
- Negative index value
- Positive index value :
Whenever you go from left to right inside the string it is known as Positive index value.
2. Negative Index value:
Whenever you go from right to left inside the string it is known as Negative index value.
Indexing : To access Any single character inside a string is called indexing.
- It is a technique by using which we can access the single character.
- Example 1 (+ve ):- var1 = “ a b c d e” ( var1[1] ===> it returns the value ‘b’ from a string.
- Example 2 (-ve) :- var1 =” a b c d e” (var1[-4] ===> it returns the value ‘b’ from a string.
Slicing : To access Any sequence of characters inside a string is called Slicing.
Slicing Syntax : Var-name[Starting index : Ending index ]
Positive Slicing:
Whenever you go from left to right to extract a sequence of characters from a string is called Positive Slicing.
Example : var1 = “ a b c d “ ( var1[1 : 2] ====> it returns the value “b” )
- Important Note 1: Ending index will never be included when we are accessing sequence of element.
- Important Note 2: Machine will always execute from left to right .
Empty String :
Whenever we are having a string which is surrounded by quotes is called empty string.
syntax : x = (“ “)
sub-string :
whenever we are accessing part of a string that is called sub-string.
Example :- (“abcd”)
String Methods :
It is a method which can be applied on string data is called string methods.
- String methods can have their own functionality to perform specific tasks on strings.
Example : x =”abc” [ x.method() ] ===>
- It checks the data whether it is a string or not .
- Apply to the functionality to the string data
- Lower() :
It will convert any upper case character inside a string into a lower case and i will ignore all the elements which are not alphabets/lower case.
Ex :- x = “Abc1B2Q”
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x.lower()
output :- ‘abc1b2q’
2. Upper():
It will convert any lower case character inside a string into a upper case and i will ignore all the elements which are not alphabets/upper case.
Ex :- x = “Abc1B2Q”
x.upper()
output :- ‘ABC1B2Q’
3. Capitalize():
It will convert the first alphabet into upper case and rest of the alphabets will be converted into lower case and any number will be ignored.
Ex :- x = “abc1B2Q”
x.capitalize()
output :- ‘Abc1b2q’
4. Title():
it will convert first alphabet of each and every words to upper and rest of the alphabets to lower case.
Ex:- var1 =”Ab2ab34ac”
var1.title()
output:-’Ab2Ab34Ac’
5. Count():
It will help you to count a single character or a sequence of character occurred in a string .
Ex :- var3 = “aaaaaaaaaaaabaaaababaaaaa”
var3.count(“aaa”)
output:- 6
When i want to check the count part of string we will use indexing.
syntax: [variablename. count(string,starting index,ending index)]
Ex:- var3 =”abaacd”
var3.count(“a”,1,4)
output: 2
6. Find():
Find method will give you the first occurrence of the specified string (index position)
Ex:- x = “bbacdbbbdbbb”
x.find(“bbb”)
output : 5
- Find method will not return negative number only it will give positive index.
Syntax :- find(substring, starting index , ending index )
Ex:- x = “ababaa”
x.find(“a”)
output : 2
Index():
This method is similar to find method .
Index will tell you the index value of first occurrence.
Difference between index and find methods:-
whenever the sub-string is not present in string find will return [ -1 ] and index will return an error.
