Increment and Decrement Operators in Python

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increment and decrement operators in python

This post was last Updated on June 24, 2022 by Himanshu Tyagi to reflect the accuracy and up-to-date information on the page.

In other object-oriented programming languages such as C++ and Java, increment (++) and decrement (–) operators add or subtract a specific number from a variable to perform a specific task in a function. Interestingly there are no increment and decrement operators in Python.

To perform an increment or decrement operation in Python, we can combine assignment and arithmetic operations, i.e., +=. For example, if you want to increment the value in x by 2, then you can write this statement in Python: x += 2 which is equivalent to this statement: x = x + 2

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Let’s now understand increment and decrement operators in Python with some examples.

Increment operator in Python

The increment operator is used to increment a variable.

Syntax:

variable=variable+value

(or)

variable+=value

Where the variable is the name that holds a value and value is to add to the variable.

Example 1:

In this example, we will create a variable with a value of 34 and perform increment operations.

#create a variable that holds a value
my_variable=34

#display actual value
print(my_variable)

#increment 34 by 7
my_variable+=7
print("After adding 7 - ",my_variable)

#increment  by 10
my_variable+=10
print("After adding 10 - ",my_variable)

#increment  by 100
my_variable+=100
print("After adding 100 - ",my_variable)

Output:

34
After adding 7 -  41
After adding 10 -  51
After adding 100 -  151

We can also add strings using the increment operator.

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Example 2: In this example, we create a string variable and add another string using the increment operator.

#create a variable that holds a string
my_variable="Hello"

#display actual string
print(my_variable)

#add the string - Codeitbro to the actual string
my_variable+=" Codeitbro"
print(my_variable)

Output:

Hello
Hello Codeitbro

We can also increment the values present in the list.

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Example: In this example, we will create a list of 5 integer values and add 6 to each element.

#create a variable that holds a list of integer elements
my_variable=[34,3,234,23,32]

#display actual list
print(my_variable)

#add every element in the list with 6
#using for loop
for i in range(len(my_variable)):
  print(my_variable[i]+6)

Output:

[34, 3, 234, 23, 32]
40
9
240
29
38

We can also increment the values present in the tuple.

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Example: In this example, we will create a tuple of 5 integer values and add 6 to each element.

#create a variable that holds a tuple of integer elements
my_variable=(34,3,234,23,32)

#display actual tuple
print(my_variable)

#add every element in the tuple with 6
#using for loop
for i in range(len(my_variable)):
  print(my_variable[i]+6)

Output:

(34, 3, 234, 23, 32)
40
9
240
29
38

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Using Increment Operator in while Loop

We will use the increment operator in the while loop to iterate all the elements.

Example: In this example, we will create a list with 5 elements and display all of them using a while loop by incrementing one by one value.

#create a variable that holds a tuple of integer elements
my_variable=(34,3,234,23,32)

#display actual tuple
print(my_variable)

i=0

#iterate every element using while loop
#using for loop
while(i < len(my_variable)):
  print(my_variable[i])
  i+=1

Output:

(34, 3, 234, 23, 32)
34
3
234
23
32

We can specify increment value as step-in for the loop.

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So by this, it will skip the n number of increments,

Syntax:

for iterator in range(start,stop,step):
  print(iterator)

Where,

  1. An iterator is used to iterate the elements.
  2. Start is the starting number.
  3. Stop is the ending number
  4. And, step is used to increment the iterator.

Example: In this example, we will iterate numbers from 0 to 10 by incrementing 3.

for i in range(0,10,3):
  #display
   print(i)

Output:

0
3
6
9

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Decrement operator in Python (–)

The decrement operator is used to decrement a variable.

Syntax:

variable=variable-value

(or)

variable-=value

Where the variable is the name that holds a value, and the value is to be subtracted from the variable.

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Example: In this example, we will create a variable with a value of 34 and perform decrement operations.

#create a variable that holds a value 
my_variable=34 

#display actual value 
print(my_variable) 

#decrement 34 by 7 
my_variable-=7 
print("After subtracting  7 - ",my_variable)  

#decrement by 10
my_variable-=10 
print("After subtracting 10 - ",my_variable) 

#decrement by 100 
my_variable-=100 
print("After subtracting 100 - ",my_variable)

Output:

34
After subtracting  7 -  27
After subtracting 10 -  17
After subtracting 100 -  -83

We can also decrement the values present in the list.

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Example: In this example, we will create a list of 5 integer values and subtract 6 to each element.

#create a variable that holds a list of integer elements
my_variable=[34,3,234,23,32]

#display actual list
print(my_variable)

#subtract every element in the list with 6
#using for loop
for i in range(len(my_variable)):
  print(my_variable[i]-6)

Output:

[34, 3, 234, 23, 32]
28
-3
228
17
26

We can also decrement the values present in the tuple.

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Example: In this example, we will create a tuple of 5 integer values and subtract 6 to each element.

#create a variable that holds a tuple of integer elements
my_variable=(34,3,234,23,32)

#display actual tuple
print(my_variable)

#subtract  every element in the tuple with 6
#using for loop
for i in range(len(my_variable)):
  print(my_variable[i]-6)

Output:

(34, 3, 234, 23, 32)
28
-3
228
17
26

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Using Decrement Operator in while Loop

We will use the decrement operator in the while loop to iterate all the elements.

Example:

In this example, we will create a list with 5 elements and display all of them using a while loop by incrementing one by one value.

#create a variable that holds a tuple of integer elements
my_variable=(34,3,234,23,32)

#display actual tuple
print(my_variable)

i=0

#iterate every element using while loop
#using for loop
while(i >= len(my_variable)):
  print(my_variable[i])
  i-=1

Output:

(34, 3, 234, 23, 32)

We can specify increment value as step-in for the loop.

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So by this, it will skip the n number of decrements,

Syntax:

for iterator in range(start,stop,step):
  print(iterator)

Where,

  1. An iterator is used to iterate the elements.
  2. Start is the starting number.
  3. Stop is the ending number
  4. And, Step is used to decrement the iterator.

Example:

In this example, we will iterate numbers from 10 to 0 by incrementing 3.

for i in range(10,0,-3):
  #display
   print(i)

Output:

10
7
4
1

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Summary

In this tutorial, we discussed increment and decrement operators in Python. We also discussed that they are not only used to add/subtract values but are also helpful in many applications like iterations. Also, they are applied to data structures like list, tuple, set, dictionary, etc.

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