How to implement guide with integer overflow in custom hash function for hash table implementation in c
I'm implementing a simple hash table in C, and I'm running into issues with integer overflow in my custom hash function. I'm using a polynomial rolling hash function for string keys but have noticed unexpected behavior when the keys are particularly long. My hash function looks like this: ```c unsigned long hash(const char *str) { unsigned long hash = 5381; int c; while ((c = *str++)) { hash = ((hash << 5) + hash) + c; // hash * 33 + c } return hash; } ``` With longer strings, I sometimes get negative values returned from the hash function, which leads to incorrect indexing in my hash table. I've tried using `unsigned long long` instead, but it doesn't seem to resolve the scenario entirely, as I still see values larger than the maximum size of my array. I'm currently using GCC version 10.2.0 on a Linux machine. I've also checked the length of the string being hashed, and it appears that normal ASCII strings up to 255 characters produce valid outputs. However, when I input strings closer to 400 characters, the hash function seems to yield unexpected results. I suspect that the scenario lies in how I'm managing or interpreting the return values from the hash function. Does anyone have suggestions on how to properly handle this case, or if there's a better approach to designing the hash function to prevent overflow?