如何最有效地检查两个字符串是否不同？

Question

I have two very large strings. How can I compare them to tell if they're identical, or if one of them is different than the other? (That way I can leave the identical strings alone and process the ones that have changed).

Answer 1

The most efficient way is to do:

$string1 == $string2

It does a bit-wise comparison of the strings, so should be at worst O(n) where n is the size of the smaller string. I don't think you're going to get much better than that (short of keeping track of the strings and if they were changed, but the way your question is worded it seems like all you want to do is compare them).

Answer 2

您可以比较哈希值，也可以创建一个包装器类，其中包含有问题的字符串和一个“ changed”标志，该标志在每次更改字符串时都设置为true 。