How can i check whether the input is a number or string

Here is an example for you

#!/usr/bin/python


str = "123456";  # Only digit in this string
print str.isdigit();

str = "this is string example....wow!!!";
print str.isdigit();

Here is a link to the string doc you should really look at
http://docs.python.org/library/stdtypes.html

Or you can use isnumeric instead of isdigit

yes i know but it prints false for float...

the isnumeric works the same as isdigit...
so i tried to reverse it...
it works for both integer and float but it gives an error if the string contains one or more integers and the rest are alphabet instead of printing "Invalid Input"...
Is there any other method to solve this prob?

while True:    
    n1 = input("Enter the first number: ")
    if n1.isalpha() == True:
        print("Invalid input!")
    else:
        n1 = float(n1)
        break

Well, you can certainly use RegEx if you want

from re import match

n.match("\d+(?:\.\d+)?")

can you explain this more in details... and i couldn't find match attribute in my python ver 3.2.2... thanks:)

Sorry, I am trying to do it but I have fever so I apologize.

I am trying to use the regex library

You will have to import re or just match

from re import match


Then you will have to use the match function.

If you say
import re

You will have to use re.match()

Also, my syntax was wrong.

Give me a second let me give you the solution

>>>no = "123.456"
>>>from re import match
>>>no.match("\d+(?:\.\d+)?")
Traceback (most recent call last):
  File "<pyshell#30>", line 1, in <module>
    no.match("\d+(?:\.\d+)?")
AttributeError: 'float' object has no attribute 'match'

Sorry for being so slow

Here is what I have so far.


>>> b = re.match("\d+(?:\.\d+)?", "171.1")
>>> b.group(0)
'171.1'
>>> b = re.match("\d+(?:\.\d+)?", "171.a")
>>> b.group(0)
'171'

Here is something you may like


>>> a = "171.123"
>>> from re import match
>>> b = match("\d+(?:\.\d+)?", a)
>>> if a == b.group(0):
...    print "A number"
...
A number
>>> a = "171.12a"
>>> b = match("\d+(?:\.\d+)?", a)
>>> if a == b.group(0):
...    print "A number"
...
>>>

At this time, I would suggest you to go with gelonida's solution and save yourself a lot of time.  Just make it a separate function like isFloat.  And check isnumeric and isFloat and then you will be all good to go.

http://stackoverflow.com/questions/379906/python-parse-string-to-float-or-int

http://rosettacode.org/wiki/Determine_if_a_string_is_numeric

Sorry for the late... N thanks for all the suggestions!