Python String isdecimal() Method

Determines whether the string contains decimal characters

Usage

The isdecimal() method returns TRUE if the string is nonempty and all characters in it are decimal characters. Otherwise, it returns FALSE.

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

string.isdecimal()

Basic Examples

Example: Check if all characters in the string are decimal characters

S = '123'
x = S.isdecimal()
print(x)    # True

Below are a few examples where isdecimal() method returns false.

Example:

# floating point number
S = '123.456'
x = S.isdecimal()
print(x)    # False
# number with thousands separator
S = '1,234,567'
x = S.isdecimal()
print(x)    # False
# empty string
S = ''
x = S.isdecimal()
print(x)    # False

isdecimal() on Unicode Decimal Characters

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

Example:

S = '\u0660'
x = S.isdigit()
print(x)    # True

isdecimal() vs isdigit() vs isnumeric()

Following examples explain the difference between the three methods.

Example: Is 42 a decimal or digit or numeric number?

print('42'.isdecimal())		# True
print('42'.isdigit())		# True
print('42'.isnumeric())		# True

Example: Is ² (Superscript Two) a decimal or digit or numeric number?

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

Example: Is ⅓ (Vulgar Fraction One Third) a decimal or digit or numeric number?

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

As you can see, the main difference between the three functions is:

  • isdecimal() method supports only Decimal Numbers.
  • isdigit() method supports Decimals, Subscripts, Superscripts.
  • isnumeric() method supports Digits, Vulgar Fractions, Subscripts, Superscripts, Roman Numerals, Currency Numerators.