How to get char from string by index?

Python.org has an excellent section on strings here. Scroll down to where it says "slice notation".

First make sure the required number is a valid index for the string from beginning or end , then you can simply use array subscript notation. use len(s) to get string length

>>> s = "python"
>>> s[3]
'h'
>>> s[6]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: string index out of range
>>> s[0]
'p'
>>> s[-1]
'n'
>>> s[-6]
'p'
>>> s[-7]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: string index out of range
>>> 

In [1]: x = "anmxcjkwnekmjkldm!^%@(*)#_+@78935014712jksdfs"
In [2]: len(x)
Out[2]: 45

Now, For positive index ranges for x is from 0 to 44 (i.e. length - 1)

In [3]: x[0]
Out[3]: 'a'
In [4]: x[45]
---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)

/home/<ipython console> in <module>()

IndexError: string index out of range

In [5]: x[44]
Out[5]: 's'

For Negative index, index ranges from -1 to -45

In [6]: x[-1]
Out[6]: 's'
In [7]: x[-45]
Out[7]: 'a

For negative index, negative [length -1] i.e. the last valid value of positive index will give second list element as the list is read in reverse order,

In [8]: x[-44]
Out[8]: 'n'

Other, index's examples,

In [9]: x[1]
Out[9]: 'n'
In [10]: x[-9]
Out[10]: '7'

Previous answers cover about ASCII character at a certain index.

It is a little bit troublesome to get a Unicode character at a certain index in Python 2.

E.g., with s = '한국中国にっぽん' which is <type 'str'>,

__getitem__, e.g., s[i] , does not lead you to where you desire. It will spit out semething like �. (Many Unicode characters are more than 1 byte but __getitem__ in Python 2 is incremented by 1 byte.)

In this Python 2 case, you can solve the problem by decoding:

s = '한국中国にっぽん'
s = s.decode('utf-8')
for i in range(len(s)):
    print s[i]