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Python Program to Count the Digits in an Integer

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Python programs to count the digits in an integer have been shown here. For example, if a number is 12345, the total number of digits is 5. The algorithm, pseudocode and time complexity of the programs have also been covered below.






1. Algorithm to count the digits in an integer


1. Take a number x as input.

2. Initialize a counter to 0 say c = 0.

3. Perform x = x / 10 and Increment c by 1 i.e. c = c + 1

4. If x = 0 stop the process and display c as output else go to step 3.




2. Pseudocode to count the digits in an integer


Input : A number $n$

Output : Total no of digits in $n$

1. Procedure countDigits($n$):

2. $c \leftarrow 0$

3. If $n == 0$:

4. $c \leftarrow 1$

5. Else:

6. Repeat until $n \neq 0$

7. $n \leftarrow n / 10$

8. $c \leftarrow c + 1$

9. Return $c$

10. End Procedure





3. Time complexity to count the digits in an integer


Time Complexity: O(log(n))

Where n is the input number.





4. Program & output to count the digits in an integer




4.1. Python Program & output to count the digits in an integer using iteration

Code has been copied
# **********************************************
#             alphabetacoder.com
# Python program to count the number of digits
# in an integer using iterative approach
# **********************************************

# initialize
count = 0

# take input of the number
num = int(input("Enter the integer = "))

# count the digits
if num == 0:
    count = 1
else:
    while num != 0:
        num = num // 10
        count = 1

# display result
print("Number of digits = ", count)

Output

Case 1:

Enter the integer = 8912

Number of digits = 4


Case 2:

Enter the integer = 5413896

Number of digits = 7





4.2. Python Program & output to count the digits in an integer using recursion

Code has been copied
#**********************************************
#             alphabetacoder.com
# Python program to count the number of digits 
# in an integer using recursive approach
#**********************************************

# recursive function to calculate
# no of digits in an integer
def count_digit(num):
    if num // 10 == 0:
        return 1
    else:
        # call function 
        return 1 + count_digit(num / 10)


def main():
    # take input of the number
    num = int(input("Enter the integer = "))

    # count the digits by calling function
    count = count_digit(num)

    # display result
    print("Number of digits = ", count)

# driver code
main()

Output

Case 1:

Enter the integer = 8912

Number of digits = 4


Case 2:

Enter the integer = 0

Number of digits = 1





4.3. Python Program & output to count the digits in an integer using logarithm

Code has been copied
#**********************************************
#             alphabetacoder.com
# Python program to count the number of digits 
# in an integer using logarithm
#**********************************************

import math

# take input of the number
num = int(input("Enter the integer = "))

# count the digits using logarithm
if num == 0:
    count = 1
else:
    count = math.floor(math.log10(num) + 1)

# display result
print("Number of digits = ", count)

Output

Case 1:

Enter the integer = 3456

Number of digits = 4


Case 2:

Enter the integer = 1234567

Number of digits = 7





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