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Possible Duplicate:
How do I check if a string is a number in Python?
Python - Parse String to Float or Int
For example, I want to check a string and if it is not convertible to integer(with int()), how can I detect that?
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Python String isnumeric() MethodThe isnumeric() method returns True if all the characters are numeric (0-9), otherwise False. Exponents, like ² and ¾ are also considered to be numeric values. "-1" and "1.5" are NOT considered numeric values, because all the characters in the string must be numeric, and the - and the .
The isalnum() method returns True if all the characters are alphanumeric, meaning alphabet letter (a-z) and numbers (0-9). Example of characters that are not alphanumeric: (space)!
Python String isdecimal() The isdecimal() method returns True if all characters in a string are decimal characters. If not, it returns False.
Use the .isdigit() method:
>>> '123'.isdigit() True >>> '1a23'.isdigit() False Quoting the documentation:
Return true if all characters in the string are digits and there is at least one character, false otherwise.
For unicode strings or Python 3 strings, you'll need to use a more precise definition and use the unicode.isdecimal() / str.isdecimal() instead; not all Unicode digits are interpretable as decimal numbers. U+00B2 SUPERSCRIPT 2 is a digit, but not a decimal, for example.
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You can always try it:
try: a = int(yourstring) except ValueError: print "can't convert" Note that this method outshines isdigit if you want to know if you can convert a string to a floating point number using float
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