STRINGS IN PYTHON
Muhammad Khokhar MANGO CLOUD TECHNOLOGIES Email: [email protected]
PYTHON PROGRAMMING CHAPTER 02 - STRINGS
Document Revision: Version 1.0 Date: 26th February 2021 Authors: Muhammad Tayyeb Khokhar Distribution: Mango Cloud Technologies
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Document Reference Strings in Python
File Name Strings in Python.pdf
Print Date 26/02/2021
Last Modified Date 26/02/2021
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Revision History
Version Date Revision Details
1.0 26/02/2021 Final
1.1
1.2
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Date Reviewer
01/03/2021 Mango Cloud Technologies
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Tel: +44 (0)1905 954701
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Table of Contents
Python Programming ...... 4 Use of Python ...... 4 Python Coding ...... 4 Strings in Python ...... 4 Writing StringS In Python ...... 4 String Indexing ...... 5 String Output ...... 5 Multiple Statements In String ...... 5 String Slicing ...... 6 Immutable Strings ...... 7 String Concatenation ...... 8 Built-in-Functions ...... 8 String Interpolation ...... 9 Floating Interpolation ...... 10
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PYTHON PROGRAMMING
Python is a widely used general-purpose, high level programming language. It was designed with an emphasis on code readability, and its syntax allows programmers to express their concepts in fewer lines of code. Python is a general-purpose coding language—which means that, unlike HTML, CSS, and JavaScript, it can be used for other types of programming and software development besides web development. That includes back end development, software development, data science and writing system scripts among other things. USE OF PYTHON
Web Development. Game Development. Machine Learning and Artificial Intelligence. Data Science and Data Visualization. Desktop GUI. Web Scraping Applications. Business Applications. CAD Applications. Embadded Applications. PYTHON CODING
Python is easy to learn. Its syntax is easy and code is very readable. ... Python allows you to write programs in fewer lines of code than most of the programming languages. The popularity of Python is growing rapidly. Dependencies. STRINGS IN PYTHON
A string in Python is a sequence of characters. It is a derived data type. Strings are immutable. This means that once defined, they cannot be changed. Many Python methods, such as replace(), join(), or split() modify strings. However, they do not modify the original string. They create a copy of a string which they modify and return to the caller. WRITING STRINGS IN PYTHON
In Python, we can write a string by using single quotes, double quotes or triple around the text. Text could be the numbers or characters. A string is simply a series of characters. Anything inside quotes is considereda string in Python, and you can use single or double or triple quotes around the statement. If we have multiple lines in a string then we have to use triple quotes.
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Table – 01
Examples of String
Single Qoutes ‘I am a single quote string’
Double Qoutes “I’m a double quote string”
Triple Qoutes “‘I am “triple” quote string”’
STRING INDEXING
Every character in a string have index value string from 0. First character in the string will have index value 0, then 1 and then continue. Table – 02
String = ‘I am string’
String character ‘I a m s t r i n g’
Index Values 0 1 2 3 4 5 6 7 8 9 10
Reverse index 0 &-11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1
Note space in a string is called white spcaing and it also have an index value.
STRING OUTPUT
Table – 03
Examples of String
Cell 1 my_string = ‘I am a python string’
Cell 2 my_string
Output ‘I am a python string’
Cell 3 print(my_string)
Output I am a python string
MULTIPLE STATEMENTS IN STRING
In python, if we want to show multiple statements in the output. We have to use print. Python will only show the last statement if we will not use print command.
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Table – 04
Other Examples of String
Cell 1 'I am a python string'
'I am better than all other programming languages'
'I am easy to learn'
Output ‘I am easy to learn’
Cell 2 print('I am a python string')
print('I am better than all other programming languages')
print('I am easy to learn')
Output I am a python string
I am better than all other programming languages
I am easy to learn
Use \n for next line, \t for Tab spacing and \\ for slash
Cell 3 print('I am python string.\n I am better than other languages \t easy to learn\\')
Output I am python string.
I am better than other languages easy to learn\
STRING SLICING
Slice allows us to grab a subsection of multiple characters, just like a slice of bread or slices of bread. The syntax is [start:stop:step] start is a numerical index for the slice. stop is the index we will go up to (but not include) step is the size of the “jump” we make Table – 05 Examples to slice a String
Cell 1 A = ‘Slice a string’
Cell 2 A[0]
Output ‘S’
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Cell 3 A[1]
Output ‘l’
Cell 4 A[5]
Output ‘ ’
Cell 5 A[1:]
Output ‘lice a string’
Cell 6 A[:5]
Output ‘Slice’
Cell 7 A[:-7]
Output ‘Slice a’
Cell 8 A[-7:]
Output ‘ string’
Cell 9 A[2:6]
Output ‘ice’
Cell 10 A[0:15:3]
Output ‘Scatn’
Cell 11 A[::-3]
Output ‘gr el’
IMMUTABLE STRINGS
Strings are immutable, which means we cannot change the strings. If we try to change the string we will get type error message. But we have other ways to make changes in the string. Table – 06 Examples to change the string
Cell 1 new_string1 = 'I am immutable, please don\'t change me'
Cell 2 new_string1[0] = 'U'
Output TypeError: 'str' object does not support item assignment
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Note: Use # in the beginning of code to disable the line
STRING CONCATENATION
In python, we cannot change the string but we can use concatenation method to change the strings. Table – 07
Example of string contatenation
Cell 1 my_name = 'Apple Cloud Technologies'
Cell 2 Correct_name = my_name[5:]
Cell 3 'Mango' + Correct_name
Output ‘Mango Cloud Technologies’
Adding strings
Cell 1 A = 'Mango '
B = 'Cloud '
C = 'Technologies'
Cell 2 D = A + B + C
Output ‘Mango Cloud Technologies’
Multiplying strings
Cell 1 My_string = ‘Python ’
Cell 2 My_string * 5
Output ‘Python Python Python Python Python’
BUILT-IN-FUNCTIONS
There are many built-in functions in python for strings. We can press tab to check what possible functions are available with the string. To execute the built-in-function use () and run Table – 08
Built-in-function .upper will change all the alphabets to capital letters
Cell 1 x = 'I am python'
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Cell 2 x.upper()
Output ‘I AM PYTHON’
Built-in-function .lower will change all the alphabets to lowercase
Cell 1 y = ‘PYTHON IS EASY TO LEARN’
Cell 2 y.lower()
Output ‘python is easy to learn’
Built-in-function .split will split the string and convert into list
Cell 1 x.split()
Output ['I', 'am', 'python']
Cell 2 y.split()
Output ['PYTHON', 'IS', 'EASY', 'TO', 'LEARN']
STRING INTERPOLATION
String interpolation is a process substituting values of variables into placeholders in a string. In simple words, injecting values in string. There are two methods for string interpolation.
.format() f-strings Table – 09
Examples of Interpolation
Cell 1 print('We are learning')
Cell 2 a = ‘Python’
Cell 3 print('We are learning {}' .format (a))
Output We are learning Python
Another example
Cell 1 print('we are learning {} {} {}' .format (a, a, a) )
Output we are learning Python Python Python
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Another example
Cell 1 b = ‘Programming’
Cell 2 print('we are learning {} {} {}' .format (a, a, b) )
Output we are learning Python Python Programming
Another example
Cell 1 print('we are learning {2} {1} {0}' .format (a, a, b) )
Output we are learning Programming Python Python
Cell 2 print('we are learning {2} {2} {2}' .format (a, a, b) )
Output we are learning Programming Programming Programming
FLOATING INTERPOLATION
Injecting floats in string. Table – 04
Example
Cell 1 Result = 12/555
Output 0.021621621621621623
Cell 2 print(‘The answer is {}’ .format (Result))
Output The answer is 0.021621621621621623
Another way
Cell 3 print(‘The answer is {x}’ .format (x=Result))
Output The answer is 0.021621621621621623
To round up decimal values
Cell 4 print('The answer is {w:1.4f}' .format (w=Result))
Output The answer is 0.0216
To display with multiple spaces.
Cell 5 print('The answer is {w:10.4f}' .format (w=Result))
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Output The answer is 0.0216
Cell 1 Name = ‘Mango Cloud Technologies’
Cell 2 Released = 2020
Cell 3 print(f’{Name} launched in {Released} December.’)
Output Mango Cloud Technologies launched in 2020 December.
Another example
Cell 1 Name = Usman
Age = 20
Cell 2 Print(f‘{Name} is {Age} years old.’)
Output Usman is 20 years old.
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