newbie str to int

[Andy Todd]

"James" <no at email.com> wrote in <9pbetr$jp83 at imsp212.netvigator.com>:

>I am switching from Perl to Python, and would
>like to convert string '123abc' to integer 123.
>
If your string is always of that form (ie a three digit integer followed by 
some non-numeric characters) then you just need;

>>> foo=int('123abc'[:3])
>>> foo
123
>>> print foo*2
246

>foo = int('123abc') # error
>foo = string.atoi('123abc') #error
>foo = eval('123abc') # error
>
>I tried the above, then tried the following.
>
>tmp = ''
>for i in '123abc':
>    if 47 < ord(i) < 58:
>        tmp += i
>foo = int(tmp) # yay

Yuck, too much Perl, must shut down brain.
Read the tutorial, in particular the section on string subscripting (in 
section 3.1.2)

>
>Why doing simple thing like this is so complicated ?

Its not complicated. The important thing to bear in mind here is the format 
of the data you wish to play about with. Where are you getting this string 
from? Is it really one string or is it a number followed by a sequence of 
characters? I find it much easier to store information in the smallest 
possible chunks to avoid these kind of problems, you can construct much 
more easily than you can slice and dice.

>
>Perl
>$foo = '123abc' + 0;
>
>Please explain in newsgroup.
>Many thanks in advance.
>
>
>

HTH,
Andy
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