In Python 2.x, just use the ord and chr functions:

>>> ord( c )
99
>>> ord( c ) + 1
100
>>> chr(ord( c ) + 1)
 d 
>>> 

Python 3.x makes this more organized and interesting, due to its clear distinction between bytes and unicode. By default, a "string" is unicode, so the above works (ord receives Unicode chars and chr produces them).

But if you re interested in bytes (such as for processing some binary data stream), things are even simpler:

>>> bstr = bytes( abc ,  utf-8 )
>>> bstr
b abc 
>>> bstr[0]
97
>>> bytes([97, 98, 99])
b abc 
>>> bytes([bstr[0] + 1, 98, 99])
b bbc 

"bad enough not having a traditional for(;;) looper"?? What?

Are you trying to do

import string
for c in string.lowercase:
    ...do something with c...

Or perhaps you re using string.uppercase or string.letters?

Python doesn t have for(;;) because there are often better ways to do it. It also doesn t have character math because it s not necessary, either.

Check this: USING FOR LOOP

for a in range(5):
    x= A 
    val=chr(ord(x) + a)
    print(val)

LOOP OUTPUT: A B C D E

I came from PHP, where you can increment char (A to B, Z to AA, AA to AB etc.) using ++ operator. I made a simple function which does the same in Python. You can also change list of chars to whatever (lowercase, uppercase, etc.) is your need.

# Increment char (a -> b, az -> ba)
def inc_char(text, chlist =  ABCDEFGHIJKLMNOPQRSTUVWXYZ ):
    # Unique and sort
    chlist =   .join(sorted(set(str(chlist))))
    chlen = len(chlist)
    if not chlen:
        return   
    text = str(text)
    # Replace all chars but chlist
    text = re.sub( [^  + chlist +  ] ,   , text)
    if not len(text):
        return chlist[0]
    # Increment
    inc =   
    over = False
    for i in range(1, len(text)+1):
        lchar = text[-i]
        pos = chlist.find(lchar) + 1
        if pos < chlen:
            inc = chlist[pos] + inc
            over = False
            break
        else:
            inc = chlist[0] + inc
            over = True
    if over:
        inc += chlist[0]
    result = text[0:-len(inc)] + inc
    return result

There is a way to increase character using ascii_letters from string package which ascii_letters is a string that contains all English alphabet, uppercase and lowercase:

>>> from string import ascii_letters
>>> ascii_letters[ascii_letters.index( a ) + 1]
 b 
>>> ascii_letters
 abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ 

Also it can be done manually;

>>> letters =  abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ 
>>> letters[letters.index( c ) + 1]
 d 

def doubleChar(str):
    result =   
    for char in str:
        result += char * 2
    return result

print(doubleChar("amar"))

output:

aammaarr

For me i made the fallowing as a test.

string_1="abcd"

def test(string_1):
   i = 0
   p = ""
   x = len(string_1)
   while i < x:
    y = (string_1)[i]
    i=i+1
    s = chr(ord(y) + 1)
    p=p+s

   print(p)

test(string_1)