Number of digits until n in python using for loop

Example 1: Count Number of Digits in an Integer using while loop

num = 3452
count = 0

while num != 0:
    num //= 10
    count += 1

print["Number of digits: " + str[count]]

Output

Number of digits: 4

In this program, the while loop is iterated until the test expression num != 0 is evaluated to 0 [false].

1. After the first iteration, num will be divided by 10 and its value will be 345. Then, the count is incremented to 1.
2. After the second iteration, the value of num will be 34 and the count is incremented to 2.
3. After the third iteration, the value of num will be 3 and the count is incremented to 3.
4. After the fourth iteration, the value of num will be 0 and the count is incremented to 4.
5. Then the test expression is evaluated to false and the loop terminates.

Example 2: Using inbuilt methods

num = 123456
print[len[str[num]]]

Output

6

In the above example, we first convert the integer value into string by using str[]. Then, we find the length of the string using len[].

n=int[input["Enter number:"]]
count=0
while[n>0]:
    count=count+1
    n=n//10
print["The number of digits in the number are:",count]

 
Case 1:
Enter number:123
The number of digits in the number are: 3
 
Case 2:
Enter number:1892
The number of digits in the number are: 4

Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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Count the number of digits in a number using python :

Using python, count the number of digits in a number. In this tutorial, we will learn how to count the total number of digits in a number using python. The program will get the input from the user and print out the result.

We will show you two different ways to calculate total digits in a number.

Solution 1 [using a while loop] :

The idea behind this solution is to keep deleting the rightmost digit of the number one by one until the number becomes zero.

Following algorithm we are going to use for this approach :

1. Take the user input and store it in a variable.
2. Create one counter variable to hold the total number count. Initialize this variable to zero at the start of the program.
3. Using a while loop, delete the rightmost digit of the number or convert the number to this new number. For example, if the number is 123, convert it to 12, then convert it to 1 and finally 0.
4. Increment the counter variable by 1 on each conversion. Do it until the number becomes zero. At the end of the while loop, this counter variable will hold the total digit count of the number.
5. Print the counter variable.

Python program :

#example 1

count = 0
number = int[input["Enter a number "]]

while [number > 0]:
  number = number//10
  count = count + 1

print ["Total number of digits : ",count]



#example 2
count = 0
number = int[input["Enter a number "]]

print ["Total number of digits : ",len[str[abs[number]]]]

You can also download this program from here.

Explanation :

1. The code is similar to the algorithm we have explained above. ‘count’ is the counter variable used to hold the total number of digits in the number. This variable is initialized to zero at the beginning.
2. We are using the input[] method to read the user input. This method returns a string, we are wrapping this value with int[] to get the integer value of the number user has entered. This value is stored in the ‘number’ variable.
3. The ‘while loop’ will run until the value of ‘number’ is greater than zero.
4. Inside the loop, we are dividing the number by 10 and assigning this new value to the number. If the value is 123, it will be 12 after the division. It is same as like deleting the last digit of the number.
5. Increment the value of count by 1 after the conversion. Eventually, the ‘number’ variable will become zero and the loop will stop.
6. Print the value of the ’count’ at the end of the program.

Example :

Solution 2 [ Using inbuilt methods ] :

Instead of using a while loop, we can directly convert the integer to a string and get the length of the string. In python, getting the length of a string is easy by using the ’len[]’ method. For converting a number to a string, we can use the ’str[]’ method.

‘abs’ is used to get the absolute value of a number. i.e. to handle the case even if the number is negative.

For example, if our input value is ’-123‘, abs[] will convert it to ’123‘. str[] will convert it to a string and len[] will return the length of the string or 3.

Python program :

#example 1

count = 0
number = int[input["Enter a number "]]

while [number > 0]:
    number = number//10
    count = count + 1

print["Total number of digits : ", count]




#example 2
count = 0
number = int[input["Enter a number "]]

print["Total number of digits : ", len[str[abs[number]]]]

You can also download this program from here.

Example :

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