Strings

 Strings

The string is a data type in Python.

A string is a sequence of characters enclosed in quotes.

In python a string is a predefined object which contains characters the string in python .

We can primarily write a string in three ways:

1.     Single quoted strings : a = ‘alok’

2.     Double quoted strings : b = “alok”

3.     Triple quoted strings : c = ‘’’ alok ‘’’

String Slicing:

A string in Python can be sliced for getting a part of the string.

Consider the following string:

 

The index in a string starts from 0 to (length-1) in Python. To slice a string, we use the following syntax:

 

Negative Indices: Negative indices can also be used as shown in the figure above. -1 corresponds to the (length-1) index, -2 to (length-2).

Slicing with skip value

We can provide a skip value as a part of our slice like this:

word = “amazing”

 

word[1:6:2]           # It will return ’mzn’

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Other advanced slicing techniques

word = ‘amazing’

 

word[:7] or word[0:7]      #It will return ‘amazing’

 

word[0:] or word[0:7]      #It will return ‘amazing’

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String Functions

Some of the most used functions to perform operations on or manipulate strings are:

1.     len() function : It returns the length of the string.

len(‘alok’)               #Returns 5

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2.     endswith(“rry”) : This function tells whether the variable string ends with the string “rry” or not. If string is “alok”, it returns for “rry” since alok ends with rry.

3.     count(“c”) : It counts the total number of occurrences of any character.

4.     capitalize() : This function capitalizes the first character of a given string.

5.     find(word) : This function finds a word and returns the index of first occurrence of that word in the string.

6.     replace(oldword, newword) : This function replaces the old word with the new word in the entire string.

Escape Sequence Characters:

Sequence of characters after backslash ‘\’ [Escape Sequence Characters]

Escape Sequence Characters comprises of more than one character but represents one character when used within the string.

Examples: \n (new line), \t (tab), \’ (single quote), \\ (backslash), etc.

Chapter 3 – Practice Set

1.     Write a Python program to display a user-entered name followed by Good Afternoon using input() function.

2.     Write a program to fill in a letter template given below with name and date.

letter = ‘’’ Dear <|NAME|>,

 

                        You are selected!

 

                        <|DATE|>

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3.     Write a program to detect double spaces in a string.

4.     Replace the double spaces from problem 3 with single spaces.

5.     Write a program to format the following letter using escape sequence characters.

letter = “Dear alok, This Python course in nice. Thanks!!”

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