What is Strings?
- String is basically a sequence which is made up of one or more UNICODE characters.
- Character in string can be any letter, digit, whitespace or any other symbol.
- String can be created by enclosing one or more characters in single, double or triple quotes.
INDEXING – Accessing characters in a string
- Individual character in a string can be accessed using indexes.
- Indexes are unique numbers assigned to each character in a string to identify them
- Index always begins from 0 and written in square brackets “[]”.
- Index must be an zero, positive or negative integer.
- We get IndexError when we give index value out of the range.
Negative Indexing
- Python allows negative indexing also.
- Negative indices are used when you want to access string in reverse order.
- Starting from the right side, the first character has the index as -1 and the last character (leftmost) has the index –n where n is length of string.

Is string immutable?
- Yes, string is immutable data type. The content of string once assigned cannot be altered than.
- Trying to alter string content may lead an error.
String operations
String supports following operations:
- Concatenation
- Repetition
- Membership
- Slicing
Concatenation
- Concatenation refers to joining two strings.
- Plus (‘+’) is used as concatenation operator.
Repetition
- Repetition as it name implies repeat the given string.
- Asterisk (‘*’) is used as repetition operator.
Membership
- Membership operation refers to checking a string or character is part or subpart of an existing string or not.
- Python uses ‘in’ and ‘not in’ as membership operator.
- ‘in’ returns true if the first string or character appears as substring in the second string.
- ‘not in’ returns true if the first string or character does not appears as substring in the second string.
Slicing
- Extracting a specific part of string or substring is called slicing
- Subset occurred after slicing contains contiguous elements
- Slicing is done using index range like string[start_index : end_index : step_value]
- End index is always excluded in resultant substring.
- Negative index can also be used for slicing.

Traversing a String
- Traversing a string refers to accessing each character of a given string sequentially.
- For or while loop is used for traversing a string
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