Changing iteration variable inside for loop in Python [duplicate]

Question

I am trying to do something as simple as changing the varible in which I am iterating over (i) but I am getting different behaviours in both Python and C.

In Python,

for i in range(10):     print i,     if i == 2:         i = 4; 

I get 0 1 2 3 4 5 6 7 8 9, but the equivalent in C:

int i; for (i = 0; i < 10; i++) {     printf("%d", i);     if (i == 2)         i = 4; } 

I get 01256789 (note that numbers 3 and 4 don't appear, as expected).

What's happening here?

Answer 1

Python has a few nice things happening in the background of for loops. For example:

for i in range(10): 

will constantly set i to be the next element in the range 0-10 no matter what.

If you want to do the equivalent in python you would do:

i = 0 while i < 10:     print(i)     if i == 2:         i = 4     else:      # these line are         i += 1 # the correct way     i += 1 # note that this is wrong if you want 1,2,4,5,6,7,8,9 

If you are trying to convert it to C then you have to remember that the i++ in the for loop will always add to the i.