how to get in python from string not one character, but two?

I have:

long_str = 'abcd'
for c in long_str:print c

and it gives me like

a
b
c
d

but i need to get

ab
cd

I'm new in python.. is there any way?

You can use slice notation. long_str[x:y] will give you characters in the range [x, y) (where x is included and y is not).

>>> for i in range(0, len(long_str) - 1, 2):
...   print long_str[i:i+2]
... 
ab
cd

Here I am using the three-argument range operator to denote start, end, and step (see http://docs.python.org/library/functions.html).

Note that for a string of odd length, this will not take the last character. If you want the last character by itself, change the second argument of range to len(long_str).