Does a nested loop advance the file pointer

Question

I have the following text file (file.txt):

1
2 inside
3
4 outside
5
6

and when I run the following code:

with open("file.txt") as f:
    for value in f:
        print("outer loop (value):         ",value,end="")
        if "inside" in value:
            lstItem = []
            lstItem.append(value)
            for i,value in enumerate(f):
                print("inner loop (index:value): ",i,value,end="")
                lstItem.append(value)
                if "outside" in value:
                    break
            print(),print(lstItem),print()

this is my output:

outer loop (value):          1
outer loop (value):          2 inside
inner loop (index:value):  0 3
inner loop (index:value):  1 4 outside

['2 inside\n', '3\n', '4 outside\n']

outer loop (value):          5
outer loop (value):          6

So I get why "2 inside" is not being included in the nested loop output (it resides outside of it), but what I don't get is why the file pointer is advanced to the next line upon calling the inner loop.

I have "2 inside" as part of the list (which is what I want), but I also would like to see "2 inside" be part of the inner loop output with its index next to it, but I can't figure out how to that. I even tried commenting out the lstItem.append(value) statement to see if it would keep the file pointer from advancing, but that just excludes that value from the list, which is not what I want.

Answer 1

I have "2 inside" as part of the list (which is what I want), but I also would like to see "2 inside" be part of the inner loop output with its index next to it

Simply print it out before entering the second loop:

    if "inside" in value:
        lstItem = []
        lstItem.append(value)
        print("inner loop (index:value): ", 0, value, end="")
        for i,value in enumerate(f, start=1):
            print("inner loop (index:value): ",i,value,end="")
            lstItem.append(value)
            if "outside" in value:
                break
        print(),print(lstItem),print()

So now there are two prints, the first with the index hardcoded as 0. Notice that the start=1 parameter is passed enumerate() so that it begins its count at 1.

Having two prints is a bit ugly. You can improve things a bit by printing after you have completed building lstItem:

    if "inside" in value:
        lstItem = []
        lstItem.append(value)
        for value in f:
            lstItem.append(value)
            if "outside" in value:
                break

        print(*('inner loop (index:value):  {} {}'.format(i, value)
                for i, value in enumerate(lstItem)), sep='')

        print(lstItem),print()

which produces this output:

outer loop (value):          1
outer loop (value):          2 inside
inner loop (index:value):  0 2 inside
inner loop (index:value):  1 3
inner loop (index:value):  2 4 outside

['2 inside\n', '3\n', '4 outside\n']

outer loop (value):          5
outer loop (value):          6