Precedence of operators and converstion in python programming with subtable example

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Precedence of operators : Precedence determine a series of steps carried out to be accomplished a task. The way we commonly represent expressions, in which operators appear between their operands, it is referred to as infix notation. For example the expression 4 + 5 is in infix notation since the + operator appears between its two operands, 4 and 5. There are other ways of representing expression called prefix and postfix notation in programming language, which operators are placed before and after their operands, respectively.

            The expression 4 + (3*5) is also in infix notation. It contains two operators, + and *. The parentheses denote that (3*5) is sub expression. Therefore, 4 and (3*5) are the operands of the addition operator, and thus the overall expression evaluates to 19. What if the parentheses were omitted, given below

            4 + 3 * 5

These are two possibilities:-

            4 + 3 * 5 -> 4 +15 = 19

            4 + 3 * 5 -> 7 * 5 = 35

However each programming language has its own rules for the other that operators are applied on task, that is called operator precedence. In the following table, higher-priority operators are placed above lower-priority ones.

Operator

Associativity

** (exponentiation)

Right-to-left

-          (negation)

Left-to-right

*(mult), / (div), // (truncating div), % (modulo)

Left-to-right

+ (addition), - (substracatin)

Left-to-right

 

Table: Operator precedence of arithmetic operators in python

For Example: Consider the following examples (Write on directly on python shell)

>>> 2+3*4

Output: 14

>>> 2*3+4

Output: 10

>>> 2*3/4

Output: 1

>>> 2*3//4

Output: 1

>>> 5+42%10

Output: 7

>>> 2*2**3

Output: 16

Note: operator precedence is the relative order that operators are applied in the evaluation of expressions.

Conversion:

Python programming language has many built-in data types. You have seen integer, float, string, list, and dictionary. Data conversion in python programming can happen in two ways, implicitly and explicitly.

These are two types of conversion:

1)      Implicit Conversion: Implicit conversions are done automatic by python. When data type conversion takes place either during compilation or during run time and is handled directly by Python for you.  

For Example: Write a program to demonstrate the use of implicit conversion.

x= 1   #Here x is integer

y = 1.0 # Here y is float

z = x + y

print(" Addition is:",z)

print("Output datatype of z is:",type(z))

Output:

 

 

 

 

 

Explicit Conversion: Explicit conversion is done by programmer. Type conversion is the explicit conversion of operands to specific type. Type conversion can be applied even if loss of information results.

 function

Example

Result

int()

int(9.9)

9

int(‘9’)

9

int(’9.7’)

ERROR

float()

float(9)

9.0

float(‘9’)

9.0

float(’9.9’

9.9

Table: conversion function int() and float() in python programming

Syntax:

            (required_data_type)(expression)

For Example: Write a program to demonstrate the use explicit conversion.

a = 5.5 #Here a is float type

b= 2.0   #Here b is float type

c = int(a + b)  # Explicit type conversion float into integer

print("Output  in Integer :", c)

c = a + b

print("Output  in Float :", c)

Output:


 




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