Every day we make decisions. When I get up in the morning, I need my shake. Now, for the shake, I need 500 ml Milk, 100 gms of Oats, 1 Banana, 1 Kiwi, and 1 Apple. In case, I don’t have any one of these, it can spell trouble. What’s the trouble ? I cannot make my shake.
In programming, we have a similar structure to situations such as these. Decision making is done with a set of statements called if, else-if, and else.
If: If a certain condition is met, we perform a block of code. Else-if: If the IF condition is not met, we perform the code written in else-if Else: If the IF condition, and the ELSE-IF condition are both not met, we perform this block of code.
Sr.No.
Statement & Description
1
An if statement consists of a boolean expression followed by one or more statements.
2
An elif statement is python’s way of saying “if the previous conditions were not true, then try this condition”.
3
The else keyword catches anything which isn’t caught by the preceding conditions.
A more picturesque, and descriptive version can be seen in this image below:
func.in: An image representing if-else statements. The order of preference is 1, 2, and then 3 .
IF statement
Example:
x = 33 y = 200 if y > x: print(“y is greater than x”)
Output:
y is greater than x
Please note the indentation. In Python, we use indentations as a way of saying that the code which follows the statement is enclosed. In other programming languages, we tend to use braces, or a parenthesis for the same. In python, things are slightly simpler, and we use indentations.
ELIF statement
Example:
x = 56 y = 56 if x > y: print(“x is greater than y”) elif x == y: print(“x and y are equal”)
Output:
x and y are equal
From the above example, we can see that because a and b both have equal values, the first block was not satisfied. Instead, the second block of code under elif, has been executed.
ELSE statement
Example:
x = 100 y = 50 if x > y: print(“x is greater than y”) elif x == y: print(“x and y are equal”) else: print(“x is greater than y”)
The heart, the soul, and the foundation of any programming language, are it’s operators. They help build the logic, and transform your ideas into functioning models. They can manipulate values, functions, and help achieve our targets when used effectively.
Types of Operators
Python language supports the following types of operators.
Arithmetic
Assignment
Bitwise
Comparison (Relational)
Identity
Logical
Membership
Now, we shall look at each arithmetic operator with examples, so that it will be a lot easier for one to understand, how does Python, and their operators, really work!
Python Arithmetic Operators
Let’s assume we have two variable, a =5 and b = 10. Thus:
Operator
Description
Example
+ Addition
Adds values on either side of the operator.
a + b = 15
– Subtraction
Subtracts right hand operand from left hand operand.
a – b = -5
* Multiplication
Multiplies values on either side of the operator
a * b = 50
/ Division
Divides left hand operand by right hand operand
b / a = 2
% Modulus
Divides left hand operand by right hand operand and returns remainder
b % a = 0
** Exponent
Performs exponential (power) calculation on operators
a**b = 5 to the power 10
//
Floor Division – The division of operands where the result is the quotient in which the digits after the decimal point are removed. But if one of the operands is negative, the result is floored, i.e., rounded away from zero (towards negative infinity) −
These operators compare the values on either sides of them and decide the relation among them. They are also called Relational operators.
Let’s assume we have two variable, a =5 and b = 10. Thus:
Operator
Description
Example
==
If the values of two operands are equal, then the condition becomes true.
(a == b) is not true.
!=
If values of two operands are not equal, then condition becomes true.
(a != b) is true.
<>
If values of two operands are not equal, then condition becomes true.
(a <> b) is true. This is similar to != operator.
>
If the value of left operand is greater than the value of right operand, then condition becomes true.
(a > b) is not true.
<
If the value of left operand is less than the value of right operand, then condition becomes true.
(a < b) is true.
>=
If the value of left operand is greater than or equal to the value of right operand, then condition becomes true.
(a >= b) is not true.
<=
If the value of left operand is less than or equal to the value of right operand, then condition becomes true.
(a <= b) is true.
Python Assignment Operators
Let’s assume we have two variable, a =5 and b = 10. Thus:
Operator
Description
Example
=
Assigns values from right side operands to left side operand
c = a + b assigns value of a + b into c
+= Add AND
It adds right operand to the left operand and assign the result to left operand
c += a is equivalent to c = c + a
-= Subtract AND
It subtracts right operand from the left operand and assign the result to left operand
c -= a is equivalent to c = c – a
*= Multiply AND
It multiplies right operand with the left operand and assign the result to left operand
c *= a is equivalent to c = c * a
/= Divide AND
It divides left operand with the right operand and assign the result to left operand
c /= a is equivalent to c = c / ac /= a is equivalent to c = c / a
%= Modulus AND
It takes modulus using two operands and assign the result to left operand
c %= a is equivalent to c = c % a
**= Exponent AND
Performs exponential (power) calculation on operators and assign value to the left operand
c **= a is equivalent to c = c ** a
//= Floor Division
It performs floor division on operators and assign value to the left operand
c //= a is equivalent to c = c // a
Python Bitwise Operators
Bitwise operator works on bits and performs bit by bit operation. Assume if a = 60; and b = 13; Now in binary format they will be as follows −
a = 0011 1100
b = 0000 1101
—————–
a&b = 0000 1100
a|b = 0011 1101
a^b = 0011 0001
~a = 1100 0011
There are following Bitwise operators supported by Python language
Operator
Description
Example
& Binary AND
Operator copies a bit to the result if it exists in both operands
(a & b) (means 0000 1100)
| Binary OR
It copies a bit if it exists in either operand.
(a | b) = 61 (means 0011 1101)
^ Binary XOR
It copies the bit if it is set in one operand but not both.
(a ^ b) = 49 (means 0011 0001)
~ Binary Ones Complement
It is unary and has the effect of ‘flipping’ bits.
(~a ) = -61 (means 1100 0011 in 2’s complement form due to a signed binary number.
<< Binary Left Shift
The left operands value is moved left by the number of bits specified by the right operand.
a << 2 = 240 (means 1111 0000)
>> Binary Right Shift
The left operands value is moved right by the number of bits specified by the right operand.
a >> 2 = 15 (means 0000 1111)
Python Logical Operators
There are following logical operators supported by Python language. Let’s assume we have two variable, a =5 and b = 10. Thus:
Operator
Description
Example
and Logical AND
If both the operands are true then condition becomes true.
(a and b) is true.
or Logical OR
If any of the two operands are non-zero then condition becomes true.
(a or b) is true.
not Logical NOT
Used to reverse the logical state of its operand.
Not(a and b) is false.
Python Membership Operators
Python’s membership operators test for membership in a sequence, such as strings, lists, or tuples. There are two membership operators as explained below:
Operator
Description
Example
in
Evaluates to true if it finds a variable in the specified sequence and false otherwise.
x in y, here in results in a 1 if x is a member of sequence y.
not in
Evaluates to true if it does not finds a variable in the specified sequence and false otherwise.
x not in y, here not in results in a 1 if x is not a member of sequence y.
Python Identity Operators
Identity operators compare the memory locations of two objects. There are two Identity operators explained below −
Operator
Description
Example
is
Evaluates to true if the variables on either side of the operator point to the same object and false otherwise.
x is y, here is results in 1 if id(x) equals id(y).
is not
Evaluates to false if the variables on either side of the operator point to the same object and true otherwise.
x is not y, here is not results in 1 if id(x) is not equal to id(y).
Python Operators Precedence
The following table lists all operators from highest precedence to lowest.
Sr.No.
Operator & Description
1
** Exponentiation (raise to the power)
2
~ + – Complement, unary plus and minus (method names for the last two are +@ and -@)
3
* / % // Multiply, divide, modulo and floor division
4
+ – Addition and subtraction
5
>> << Right and left bitwise shift
6
&Bitwise ‘AND’
7
^ |Bitwise exclusive `OR’ and regular `OR’
8
<= < > >= Comparison operators
9
<> == != Equality operators
10
= %= /= //= -= += *= **= Assignment operators
11
is is not Identity operators
12
in not in Membership operators
13
not or and Logical operators
In case, you have any questions, feel free to mention your questions as comments to this specific post. I will try and answer at the earliest.
The word variable in itself speaks dynamism. It’s value, quantity, and essence, can change from time to time. In programming as well, your value changes from time to time.
In Python, variables are used to store data, like string, numbers, date-time etc. When you create a variable, a little portion is reserved within your computer memory to store this value of the variable. The value of a variable has to be assigned by you.
Types of variables
Python has five standard data types:
Numbers
String
List
Tuple
Dictionary
Creating a variable
In Python, a variable does not need to be declared while creating or before adding a value to it. Python variables are usually dynamically typed, that is, the type of the variable is interpreted during run-time and you don’t need to specify the type of a variable.
The following program shows how to use string and integer type variables:
Example
x = 10 # Integer variable y = “Hello World” # String variable # Displaying variables value print(x) print(y)
Output
10 Hello World
Checking the type of a variable
With the method type(), we can know the type of variable we have created. It could be int, str, is used to get the type of a created variable.
Example
var1 = ‘Hello World’ print(type(var1))
Output
<class ‘str’>
ImportantRules for Variables
Variables cannot start with a number, but can be Alpha-Numeric. Additionally, they also support underscores – hence the total range is from A-Z, a-z, 0-9, and _.
Variables are strictly case-sensitive, thus You and you are different variables
Data Type Conversion
Sometimes, due to functional reasons, we need to convert variables. For this purpose, python is quite straight forward. To convert between types, you simply use the type name as a function. A common industry jargon is ‘Type Casting‘.
There are several built-in functions to perform conversion from one data type to another. These functions return a new object, with the changed data type 🙂.
Sr.No.
Function & Description
1
int(x ): Converts x to an integer.
2
long(x): Converts x to a long integer.
3
float(x): Converts x to a floating-point number.
4
str(x): Converts object x to a string representation.
5
tuple(s): Converts s to a tuple.
6
list(s): Converts s to a list.
7
set(s): Converts s to a set.
8
dict(d): Creates a dictionary. d must be a sequence of (key,value) tuples.
You have no idea how long I have waited to have my own portal in order to share information, with one, and all. With a lot of patience, time, and effort, I’d like to begin my journey of being an open book, solving some of your problems, and in that process also learning a lot more from you.
To begin with, I would like to introduce Python to you as a concept I like to call SEQL – Simple Elegant Quick Learn. So instead of SQL, we have SEQL.
Python is a popular programming language. It was created by Guido van Rossum, and released in 1991, and has a wide array of uses, particularly:
Web Development
Software Development,
Scripting
Machine Learning
Artificial Intelligence
Owing to it’s Simple syntax, and an Elegant programming structure, it is Quick to execute and Learn. Over the course of my forthcoming posts, you shall come across a wide range of tutorials, quick solutions, tips, and tricks, that I have documented, learned, and experienced over time.
With my trivial, yet foundational, exposure to Python, I want to document my understanding of programming, and make it as easy for you to grasp the fundamental concepts of programming.
In case you have any doubts, feel free to write down your questions in the comments below. I will try and respond to each one of them.
Before I leave, one has to cut the ribbon by a simple saying….wait for it….”Hello World”.
