How to find the type ...

**robert.dowell@gmail.com** · Dec 9 '05, 05:05 PM

Re: How to find the type ...

>>> thisisastring = "1"[color=blue][color=green][color=darkred]
>>> thisisanint = 1
>>> type(thisisastr ing)[/color][/color][/color]
<type 'str'>[color=blue][color=green][color=darkred]
>>> type(thisisanin t)[/color][/color][/color]
<type 'int'>[color=blue][color=green][color=darkred]
>>> thisisastring = int(thisisastri ng)
>>> thisisanint = str(thisisanint )
>>> type(thisisastr ing)[/color][/color][/color]
<type 'int'>[color=blue][color=green][color=darkred]
>>> type(thisisanin t)[/color][/color][/color]
<type 'str'>[color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

**Magnus Lycka** · Dec 9 '05, 05:15 PM

Re: How to find the type ...

Lad wrote:[color=blue]
> Hello
> How can I find out in Python whether the operand is integer or a
> character and change from char to int ?[/color]

I'm not sure what you mean by "character" in a Python context.
A string? "i = int(i)" will make sure both 5 and "5" are used
as 5, and "five" will be rejected with a ValueError.
[color=blue][color=green][color=darkred]
>>> def f(x):[/color][/color][/color]
.... i = int(x)
.... print i, type(i)
....[color=blue][color=green][color=darkred]
>>> f(5)[/color][/color][/color]
5 <type 'int'>[color=blue][color=green][color=darkred]
>>> f('42')[/color][/color][/color]
42 <type 'int'>[color=blue][color=green][color=darkred]
>>> f('infinity')[/color][/color][/color]
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "<stdin>", line 2, in f
ValueError: invalid literal for int(): infinity

**Steve Holden** · Dec 9 '05, 05:25 PM

Re: How to find the type ...

Lad wrote:[color=blue]
> Hello
> How can I find out in Python whether the operand is integer or a
> character and change from char to int ?
> Regards,
> L.
>[/color]
Easiest would just be to apply the int() type function to whatever you
have and trap any resulting exception.
[color=blue][color=green][color=darkred]
>>> getInt(1)[/color][/color][/color]
1[color=blue][color=green][color=darkred]
>>> getInt("32767")[/color][/color][/color]
32767[color=blue][color=green][color=darkred]
>>> getInt('have a banana')[/color][/color][/color]
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "<stdin>", line 5, in getInt
ValueError: getInt called with non-integer value

Unfortunately we should also consider:

[color=blue][color=green][color=darkred]
>>> getInt("3.14159 ")[/color][/color][/color]
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "<stdin>", line 5, in getInt
ValueError: getInt called with non-integer value[color=blue][color=green][color=darkred]
>>> getInt(3.14159)[/color][/color][/color]
3[color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

which may or may not be what you want.

regards
Steve
--
Steve Holden +44 150 684 7255 +1 800 494 3119
Holden Web LLC www.holdenweb.com
PyCon TX 2006 www.python.org/pycon/

**Rocco Moretti** · Dec 9 '05, 05:25 PM

Re: How to find the type ...

robert.dowell@g mail.com wrote:[color=blue][color=green][color=darkred]
>>>>thisisastri ng = "1"
>>>>thisisani nt = 1
>>>>type(thisis astring)[/color][/color]
>
> <type 'str'>
>[color=green][color=darkred]
>>>>type(thisis anint)[/color][/color]
>
> <type 'int'>
>[color=green][color=darkred]
>>>>thisisastri ng = int(thisisastri ng)
>>>>thisisani nt = str(thisisanint )
>>>>type(thisis astring)[/color][/color]
>
> <type 'int'>
>[color=green][color=darkred]
>>>>type(thisis anint)[/color][/color]
>
> <type 'str'>[/color]
[color=blue][color=green][color=darkred]
>>> print repr(thisisastr ing)[/color][/color][/color]
1[color=blue][color=green][color=darkred]
>>> print repr(thisisanin t)[/color][/color][/color]
'1'[color=blue][color=green][color=darkred]
>>> thisisastring = 'a'
>>> thisisanint = 98
>>> thisisastring = ord(thisisastri ng) #Using ASCII rep.
>>> thisisanint = chr(thisisanint )
>>> type(thisisastr ing)[/color][/color][/color]
<type 'int'>[color=blue][color=green][color=darkred]
>>> type(thisisanin t)[/color][/color][/color]
<type 'str'>[color=blue][color=green][color=darkred]
>>> print repr(thisisastr ing)[/color][/color][/color]
97[color=blue][color=green][color=darkred]
>>> print repr(thisisanin t)[/color][/color][/color]
'b'

**Steven Bethard** · Dec 9 '05, 05:25 PM

Re: How to find the type ...

Lad wrote:[color=blue]
> How can I find out in Python whether the operand is integer or a
> character and change from char to int ?[/color]

Python doesn't have a separate character type, but if you want to
convert a one-character string to it's ASCII number, you can use ord():
[color=blue][color=green][color=darkred]
>>> ord('A'), ord('z')[/color][/color][/color]
(65, 122)

The answer to your first question is that you probably don't want to.
You probably want two separate functions, one that takes an integer and
one that takes a character. What's your actual function look like?

STeVe

**Xavier Morel** · Dec 9 '05, 05:35 PM

Re: How to find the type ...

Lad wrote:[color=blue]
> Hello
> How can I find out in Python whether the operand is integer or a
> character and change from char to int ?
> Regards,
> L.
>[/color]
You may want to try the "type" command.
And there is no character type in cPython (unless you're using ctypes
that is)

There is not much point though, you can use the "int" construct on your
expression, Python'll try to convert the expression to an integer by
itself (and throw an exception if it can't)
[color=blue][color=green][color=darkred]
>>> a = 3
>>> int(a)[/color][/color][/color]
3[color=blue][color=green][color=darkred]
>>> a = "3"
>>> int(a)[/color][/color][/color]
3[color=blue][color=green][color=darkred]
>>> a = "e"
>>> int(a)[/color][/color][/color]

Traceback (most recent call last):
File "<pyshell#5 >", line 1, in -toplevel-
int(a)
ValueError: invalid literal for int(): e[color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

You can even do base conversions with it:
[color=blue][color=green][color=darkred]
>>> a="0xe"
>>> int(a)[/color][/color][/color]

Traceback (most recent call last):
File "<pyshell#7 >", line 1, in -toplevel-
int(a)
ValueError: invalid literal for int(): 0xe[color=blue][color=green][color=darkred]
>>> int(a,16) # Silly me, 0xe is not a decimal[/color][/color][/color]
14[color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

**Martin Christensen** · Dec 9 '05, 05:55 PM

Re: How to find the type ...

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Hash: SHA1
[color=blue][color=green][color=darkred]
>>>>> "Lad" == Lad <python@hope.cz > writes:[/color][/color][/color]
Lad> How can I find out in Python whether the operand is integer or a
Lad> character and change from char to int ?

In Python, the canonical way of doing this would be to simply assume
that the argument can be converted to an integer and catch any errors
that occur:

def f(x):
try:
x = int(x)
except ValueError:
# It's a non-number string.
do stuff
except TypeError:
# It's neither a number nor a string.
do some other stuff

Martin
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**Scott David Daniels** · Dec 9 '05, 10:35 PM

Re: How to find the type ...

Xavier Morel wrote:[color=blue]
> You can even do base conversions with it:[color=green][color=darkred]
> >>> a="0xe"
> >>> int(a)[/color][/color]
> Traceback (most recent call last):
> File "<pyshell#7 >", line 1, in -toplevel-
> int(a)
> ValueError: invalid literal for int(): 0xe[color=green][color=darkred]
> >>> int(a,16) # Silly me, 0xe is not a decimal[/color][/color]
> 14[/color]
Or even say "look to the text for a clue about the base":
[color=blue][color=green][color=darkred]
>>> int('0xe', 0)[/color][/color][/color]
14[color=blue][color=green][color=darkred]
>>> int('010', 0)[/color][/color][/color]
8[color=blue][color=green][color=darkred]
>>> int('10', 0)[/color][/color][/color]
10

--
-Scott David Daniels
scott.daniels@a cm.org

**Lad** · Dec 10 '05, 08:35 PM

Re: How to find the type ...

Thank you ALL for help and explanation
Regards,
L.