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Python String isdecimal() Function

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

note

Decimal characters are those that can be used to form numbers in base 10 [0-9].

Unicode decimal character such as U+0660 (Arabic-Indic Digit Zero) is also considered as a decimal.

Syntax​

my_string.isdecimal()

isdecimal() Parameters​

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

isdecimal() Return Value​

Python String isdecimal() function returns:

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

Examples​

Example 1: Check if a String is decimal with isdecimal()​

The isdecimal() method returns True if all characters in the string are decimal characters.

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

output

True

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

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

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

output

False

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

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

output

False

For example, empty string is not decimal:

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

output

False

Example 2: Check if a String with Unicode Decimal Characters is decimal with isdecimal()​

Unicode characters, like U+0660 (Arabic-Indic Digit Zero), are also considered as decimal characters.

my_str = '\u0660'
result = my_str.isdigit()
print(result) # Output: True

output

True

But not all Unicode characters are decimal characters!

my_str1 = '\u00B23455' # my_str1 = '²3455'
my_str2 = '\u00BD'      # my_str2 = '½'

print(my_str1.isdecimal()) # Output: False
print(my_str2.isdecimal()) # Output: False

output

False
False

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

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

  • isdecimal() method supports only Decimal Number

  • isdigit() method supports Decimals, Subscripts, Superscripts

  • 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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