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Python String isdigit() Function

The String isdigit() method returns True if the string is not empty and all the characters are digits. Otherwise, it returns False.

note

Unicode characters such as superscript digits (like ¹ , ², ³) and subscripts digits (like ₁, ₂, ₃) are also considered as digits.

Syntax​

my_string.isdigit()

isdigit() Parameters​

Python String isdigit() function does not take any parameters.

isdigit() Return Value​

Python String isdigit() function returns:

  • True if ALL characters in the string are digits.
  • False if AT LEAST ONE character is NOT a digit.

Examples​

Example 1: Check if a String is digit with isdigit()​

The isdigit() method returns True if all characters in the string are digits.

my_str = '123'
result = my_str.isdigit()
print(result) # Output: True

output

True

The isdecimal() method returns False if at least one character is not a digit.

For example, string of a float point number is not digit:

my_str = '123.456'
result = my_str.isdigit()
print(result) # Output: False

output

False

For example, string of number with thousands separator is not digit:

my_str = '1,234,567'
result = my_str.digit()
print(result) # Output: False

output

False

For example, empty string is not digit:

my_str = ''
result = my_str.isdigit()
print(result) # Output: False

output

False

Example 2: Check if a String with Unicode Digit Characters is digit with isdecimal()​

Unicode characters, like U+0660 (Arabic-Indic Digit Zero), subscripts and superscripts, are also considered as digits.

my_str1 = '\u0660'     
my_str2 = '\u00B23455' # my_str2 = '²3455'
my_str3 = '\u20823455' # my_str2 = '₂3455'

print(my_str1.isdigit()) # Output: True
print(my_str2.isdigit()) # Output: True
print(my_str3.isdigit()) # Output: True

output

True
True
True

Special Unicode characters like circled digits ⑥ are also considered as digits.

my_str = '\u2465' # Special Unicode ⑥
print(my_str.isdigit()) # Output: True

output

True

But not all Unicode characters are valid digits!

For example, Vulgar Fractions are not digits!

my_str = '\u00BD'      # my_str2 = '½'

print(my_str.isdigit()) # Output: False

output

False

isdigit() method vs isdecimal() method vs isnumeric() method​

The main difference between the isdigit(), isdecimal() and isnumeric() methods is that:

  • isdigit() method supports Decimals, Subscripts, Superscripts

  • isdecimal() method supports only Decimal Number

  • isnumeric() method supports Digits, Vulgar Fractions, Subscripts, Superscripts, Roman Numerals, Currency Numerators.

Example with '123' as String:

print('123'.isdecimal())        # Output True
print('123'.isdigit())          # Output True
print('123'.isnumeric())        # Output True

output

True
True
True

Example with Superscript Two '²' (that is '\u00b2') as String:

print('\u00b2'.isdecimal())     # Output False
print('\u00b2'.isdigit())       # Output True
print('\u00b2'.isnumeric())     # Output True

output

False
True
True

Example with Vulgar Two '⅓' (that is '\u2153') as String:

print('\u2153'.isdecimal())     # Output False
print('\u2153'.isdigit())       # Output False
print('\u2153'.isnumeric())     # Output True

output

False
False
True

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