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In Python, how do you find the number of digits in an integer?
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The length of an integer field is defined in terms of number of digits; it can be 3, 5, 10, or 20 digits long. A 3-digit field takes up 1 byte of storage; a 5-digit field takes up 2 bytes of storage; a 10-digit field takes up 4 bytes; a 20-digit field takes up 8 bytes.
The formula will be integer of (log10(number) + 1). For an example, if the number is 1245, then it is above 1000, and below 10000, so the log value will be in range 3 < log10(1245) < 4. Now taking the integer, it will be 3. Then add 1 with it to get number of digits.
The integer, float, Boolean, and complex types are examples of built-in data types that you can't use with len() . The function raises a TypeError when the argument is an object of a data type that doesn't have a length.
A variable length integer is an encoding of 64-bit unsigned integers into between 1 and 9 bytes. The encoding has the following properties: Smaller (and more common) values use fewer bytes and take up less space than larger (and less common) values.
If you want the length of an integer as in the number of digits in the integer, you can always convert it to string like str(133) and find its length like len(str(123)).
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Without conversion to string
import math digits = int(math.log10(n))+1 To also handle zero and negative numbers
import math if n > 0: digits = int(math.log10(n))+1 elif n == 0: digits = 1 else: digits = int(math.log10(-n))+2 # +1 if you don't count the '-' You'd probably want to put that in a function :)
Here are some benchmarks. The len(str()) is already behind for even quite small numbers
timeit math.log10(2**8) 1000000 loops, best of 3: 746 ns per loop timeit len(str(2**8)) 1000000 loops, best of 3: 1.1 µs per loop timeit math.log10(2**100) 1000000 loops, best of 3: 775 ns per loop timeit len(str(2**100)) 100000 loops, best of 3: 3.2 µs per loop timeit math.log10(2**10000) 1000000 loops, best of 3: 844 ns per loop timeit len(str(2**10000)) 100 loops, best of 3: 10.3 ms per loop If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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