Python 4.4 - Points to remember

 

Points to remember

·         Operators are symbols used to perform some operations on operands. For example, in statement z=x+y, ‘+’ and ‘=’ are operators and ‘x’, ‘y’ and ‘z’ are operands. Addition operator is used here to add two operands ‘x’ and ‘y’ and assignment ‘=’ operator is used to assign the result of addition to operand ‘z’.

·         Operators which operate upon single operand are called Unary operators such as unary ‘+’ and unary ‘-’. For example, -5, -6.8

·         Operators which operate upon two operands are called Binary operators such as addition, subtraction etc. For example, 5+7, 45-23, x+y, x/y

·         Arithmetic operators perform mathematical calculations such as addition, subtraction, multiplication, division. Modulus, floor division and exponentiation.

·         Assignment operator ‘=’ is used to assign a value to the left side variable.

·         There are compound assignment operators such as ‘+=’, ‘-=’, ‘*=’, ‘/=’, ‘//=’, ‘%=’ and ‘**=’ which are used to represent short hand notations of actual statements.

·         Relational operators are used to compare two values. The result of a relational statement is always either True or False.

·         Logical operators are used to combine multiple conditions together.    

·         ‘5<7’, ‘8==5’, ‘3!=5’, ‘6>=3’ are relational statements since they contain relational operators. And the result of a relation statement is always either True or False.

·         ‘5<7 and 8>2’, ‘8==5 or 7<43’ are logical statements since they contain logical operators. And the result of a logical statement is always either True or False.

·         ‘x=x+5’, ‘x=x-8’, ‘x=x/12’ can be written as ‘x+=5’, ‘x-=8’, ‘x/=12’ which are short hand notations of those statements.

·         Bitwise operators work on each bit of a number i.e. they work on binary numbers.

·         Identity operators compare memory locations of two objects not the values.

·         Membership operators are used to check whether an element is present in a sequence or not.

·         Which operator will be executed first in an expression when there are many operators is called operator precedence.

·         When multiple operators with same precedence are used in a single expression then where to start execution i.e. from Left to Right or from Right to Left, is known as operator associativity.

·         A module is a file that contains Python code such as our Python programs and pre-defined Python libraries.

·         We can import a module in a program in many ways using ‘import’ keyword such as –

1.       import modulename

2.       import modulename as nickname

3.       from modulename import object1, object2, …..

4.       from modulename import * 

 

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