Question: In some string problems l have used hashing for checking a substring is present in a given string in o(1) [i.e for matching a substring] but i had a doubt that how can we say that hashing doesn't undergo collision while checking for matching substrings?

Note: the hashing logic is the same logic that used in rabin karp algorithm for patter matching. Please correct me if am wrong in any case.

Everyone are invited to solve my doubt

Thanks in Advance !!!