Python's for loops are different. i gets reassigned to the next value every time through the loop.

The following will do what you want, because it is taking the literal version of what C++ is doing:

i = 0
while i < some_value:
    if cond...:
        i+=1
    ...code...
    i+=1

Here's why:

in C++, the following code segments are equivalent:

for(..a..; ..b..; ..c..) {
    ...code...
}

and

..a..
while(..b..) {
     ..code..
     ..c..
}

whereas the python for loop looks something like:

for x in ..a..:
    ..code..

turns into

my_iter = iter(..a..)
while (my_iter is not empty):
    x = my_iter.next()
    ..code..

You can use itertools for that:

If you want to go to 1024 and back once, you can use:

from itertools import chain

for i in chain(range(0,1024),range(1024,0,-1)):
    print(i)

In case you will need this quite often, you can use a function to generate the iterable:

def range_back(start,end):
    return chain(range(start,end),range(end,start,-1))

and use it like:

for i in range_back(0,1024):
    print(i)

Or if you want to do this an infinite amount of times:

from itertools import chain, cycle

for i in cycle(chain(range(0,1024),range(1024,0,-1))):
    print(i)

Try something like this instead:

import string

def getAvailableLetters(lettersGuessed):
    return sorted(set(string.ascii_lowercase) - set(lettersGuessed))

lettersGuessed = ['e', 'i', 'k', 'p', 'r', 's']
getAvailableLetters(lettersGuessed)

You can just use while for this:

i = 0 // maybe 1 would be better?
while i < someSize:
    doSomething()
    i *= 5

Just be aware that this is an infinite loop (unless someSize is zero, of course) if, as you did in your title, you start at zero. It doesn't matter how many time you multiply zero by five, you'll always end up with zero.

As an aside, there's nothing to stop you creating your own iterator, even one that calls a function to decide the next value and whether the iterator should stop.

The following code provides such a beast, one where you specify the initial value and a pair of functions to update and check the values (implemented as lambdas in the test code):

# Iterator which uses a start value, function for calculating next value,
# and function for determining whether to continue, similar to standard
# C/C++ for loop (not C++ range-for, Python already does that).

class FuncIter(object):
    def __init__(self, startVal, continueProc, changeProc):
        # Store all relevant stuff.

        self.currVal = startVal
        self.continueProc = continueProc
        self.changeProc = changeProc

    def __iter__(self):
        return self

    def __next__(self):
        # If allowed to continue, return current and prepare next.

        if self.continueProc(self.currVal):
            retVal = self.currVal
            self.currVal = self.changeProc(self.currVal)
            return retVal

        # We're done, stop iterator.

        raise StopIteration()

print([item for item in FuncIter(1, lambda x: x <= 200, lambda x: x * 4 - 1)])

The expression:

FuncIter(1, lambda x: x <= 200, lambda x: x * 4 - 1)

generates the values that you would get with the equivalent C/C++ for statement:

for (i = 1; i <= 200; i = i * 4 - 1)

as shown by the output:

[1, 3, 11, 43, 171]

I think this is an XY problem. Explain exactly what you're trying to accomplish and why and how it's not working. for x in y: is the way it ought to be expressed in 99.9% of cases.

For loops exist in Python; they just have a different syntax.

for i in range(len(my_string_or_list)):
    print(my_string_or_list[i])

for i,v in enumerate(my_string_or_list):
    print(f"Index {i} contains {v}")

You can use the re module (regular expression) to extract the separate portions of an email address string into a list, and then get gmail from there:

import re
re.split(r"[@.]", "[email protected]")[1] # 'gmail'