Question

I was wondering how to achieve the following in python:

for( int i = 0; cond...; i++)
  if cond...
    i++; //to skip an run-through

I tried this with no luck.

for i in range(whatever):
  if cond... :
    i += 1

Answer 1

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..