Convert string into integer

Question

How can I convert string into integer and remove every character from that change. Example:

S = "--r10-" I want to have this: S = 10

This not work:

S = "--10-" int(S)

I'm not sure whether you know how you strings look like but you can always use regular expressions to get the relevant information out. \d gives you numbers — Daniel Wehner
– Daniel Wehner, Commented Nov 15, 2011 at 21:32

Sven Marnach · Accepted Answer · 2011-11-15 22:00:24Z

You can use filter(str.isdigit, s) to keep only those characters of s that are digits:

>>> s = "--10-" >>> int(filter(str.isdigit, s)) 10

Note that this might lead to unexpected results for strings that contain multiple numbers

>>> int(filter(str.isdigit, "12 abc 34")) 1234

or negative numbers

>>> int(filter(str.isdigit, "-10")) 10

Edit: To make this work for unicode objects instead of str objects, use

int(filter(unicode.isdigit, u"--10-"))

I have this message in my code: 'descriptor 'isdigit' requres a 'str' object but recived a 'unicode' :( any suggestion?
You could also use operator.methodcaller("isdigit") so it will work with both str and unicode.

MatLecu · Accepted Answer · 2011-11-15 21:33:33Z

remove all non digits first like that:

int(''.join(c for c in "abc123def456" if c.isdigit()))

Fred Foo · Accepted Answer · 2011-11-15 21:29:26Z

1

You could just strip off - and r:

int("--r10-".strip('-r'))

answered Nov 15, 2011 at 21:29

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Comments

Uğur Gümüşhan · Accepted Answer · 2011-11-15 21:31:28Z

0

use regex replace with /w to replace non word characters with "" empty string. then cast it

answered Nov 15, 2011 at 21:31

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Steven Rumbalski · Accepted Answer · 2011-11-15 22:06:10Z

I prefer Sven Marnach's answer using filter and isdigit, but if you want you can use regular expressions:

>>> import re >>> pat = re.compile(r'\d+') # '\d' means digit, '+' means one or more >>> int(pat.search('--r10-').group(0)) 10

If there are multiple integers in the string, it pulls the first one:

>>> int(pat.search('12 abc 34').group(0)) 12

If you need to deal with negative numbers use this regex:

>>> pat = re.compile(r'\-{0,1}\d+') # '\-{0,1}' means zero or one dashes >>> int(pat.search('negative: -8').group(0)) -8

Zile Rehman · Accepted Answer · 2013-03-28 22:57:22Z

This is simple and does not require you to import any packages.

def _atoi(self, string): i = 0 for c in string: i += ord(c) return i