Python String isdecimal() Method

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

Syntax

my_string.isdecimal()

isdecimal() Parameters

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

isdecimal() Return Value

Python String isdecimal() method 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