Python for loop multi-dimensional array indexing issue-CodePudding

I have the first two strings in a string list strs that is guaranteed to have length of at least 2. I want to compare their letters against each other, and perform a task when their letters are identical. Here is the code I am using:

        iter_len = len(strs[1])
        if (len(strs[0]) >= len(strs[1])):
            iter_len = len(strs[0])
        
        for i in range (0, iter_len, 1):
            if (strs[0][i] == strs[1][i]):
                [do a thing]

However, when I run this, I get a IndexError: string index out of range for the if (strs[0][i] == strs[1][i]): line. I don't quite understand why this is happening, as the first if statement should ensure that iter_len is the minimum length between strs[0] and strs[1], and should prevent the index from going over. Any advice is much appreciated.

CodePudding user response：

If you need to iterate through two sequences in lockstep, it's generally best practice to use zip:

for a,b in zip(strs[0], strs[1]):
    if a == b:
        #[do a thing]

This will deal with the issue of one sequence being longer than the other.

If you need the index, you can use enumerate with your zip:

for i, (a, b) in enumerate(zip(strs[0], strs[1])):
    if a == b:
        #[do a thing with i]