Is there a method that I can use to check if a raw_input is an integer?
I found this method after researching in the web:
print isinstance(raw_input("number: ")), int)
but when I run it and input 4 for example, I get FALSE. I'm kind of new to python, any help would be appreciated.
isinstance(raw_input("number: ")), int) always yields False because raw_input return string object as a result.
Use try: int(...) ... except ValueError:
number = raw_input("number: ")
try:
int(number)
except ValueError:
print False
else:
print True
or use str.isdigit:
print raw_input("number: ").isdigit()
NOTE The second one yields False for -4 because it contains non-digits character. Use the second one if you want digits only.
UPDATE As J.F. Sebastian pointed out, str.isdigit is locale-dependent (Windows). It might return True even int() would raise ValueError for the input.
>>> import locale
>>> locale.getpreferredencoding()
'cp1252'
>>> '\xb2'.isdigit() # SUPERSCRIPT TWO
False
>>> locale.setlocale(locale.LC_ALL, 'Danish')
'Danish_Denmark.1252'
>>> '\xb2'.isdigit()
True
>>> int('\xb2')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: '\xb2'
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