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,
- An iterator is used to iterate the elements.
- Start is the starting number.
- Stop is the ending number
- 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
Also Read: How To Sort a List of Tuples in Python
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.
Also Read: Arithmetic Operators in Python [With Examples]
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.
Also Read: How to Convert Python Tuples to Lists
So by this, it will skip the n number of decrements,
Syntax:
for iterator in range(start,stop,step): print(iterator)
Where,
- An iterator is used to iterate the elements.
- Start is the starting number.
- Stop is the ending number
- 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
Also Read: How to Handle String Index Out of Range Error In Python
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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