String Manipulation in Python
Strings are sequences of characters. There are numerous algorithms for processing strings, including for searching, sorting, comparing and transforming. Python strings are "immutable" which means they cannot be changed after they are created . To create a string, put the sequence of characters inside either single quotes, double quotes, or triple quotes and then assign it to a variable.
Access characters in a string
In order ot access characters from String, use the square brackets [] for slicing along with the index or indices to obtain your characters. Python String index starts from 0.
Python allows negative indexing for its sequences.
The index of -1 refers to the last item, -2 to the second last item and so on.
String Concatenation
Joining of two or more strings into a single one is called concatenation. Python uses "+" operator for joining one or more strings
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Reverse a String
In Python Strings are sliceable. Slicing a string gives you a new string from one point in the string, backwards or forwards, to another point, by given increments. They take slice notation or a slice object in a subscript:
The subscript creates a slice by including a colon within the braces:
It works by doing [begin:end:step] - by leaving begin and end off and specifying a step of -1, it reverses a string.
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String Methods
Python has several built-in methods associated with the string data type. These methods let us easily modify and manipulate strings. Built-in methods are those that are defined in the Python programming language and are readily available for us to use. Here are some of the most common string methods.
Python String len() method
String len() method return the length of the string.
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Python String count() method
String count() method returns the number of occurrences of a substring in the given string.
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Python String index() method
String index() method returns the index of a substring inside the given string.
end(optional) by default its equal to the length of the string.
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Python String upper() method
String upper() convert the given string into Uppercase letters and return new string.
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Python String lower() method
String lower() convert the given string into Lowercase letters and return new string.
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Python String startswith() method
String startswith() method returns Boolean TRUE, if the string Starts with the specified substring otherwise, it will return False.
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Python String endswith() method
String endswith() method returns Boolean TRUE, if the string Ends with the specified substring otherwise, it will return False.
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Python String split() method
String split() method break up a string into smaller strings based on a delimiter or character.
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example
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example
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Python returned split string as a List
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Python String join() method
String join() is a string method which returns a string concatenated with the elements of an iterable.
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Python String find() method
String find() return the index position of the first occurrence of a specified string. It will return -1, if the specified string is not found.
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Python String strip() method
String strip() remove the specified characters from both Right hand side and Left hand side of a string (By default, White spaces) and returns the new string.
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Python String rstrip() method
String rstrip() returns a copy of the string with trailing characters removed.
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Python String lstrip() method
String lstrip() returns a copy of the string with leading characters removed.