👀 Views: 54 💬 Answers: 1 📅 Created: 2025-06-07

c hash-table integer-overflow C

I've hit a wall trying to Could someone explain I'm implementing a simple hash table in C, and I'm working with an scenario with integer overflow in my custom hash function. The function is supposed to take a string and return an unsigned integer as the hash value. However, for certain input strings, the returned value is unexpectedly negative, which leads to incorrect indexing in my hash table. Here's the code for my hash function: ```c unsigned int hash(const char *str) { unsigned int hash = 5381; int c; while ((c = *str++)) { hash = ((hash << 5) + hash) + c; // hash * 33 + c } return hash; } ``` I've noticed that for long strings, especially those that contain special characters, the `hash` variable is overflowing. I've tried changing the type of `hash` from `unsigned int` to `uint64_t` for higher capacity, but the scenario continues. I also looked into using a different hashing algorithm, but I wanted to stick with this one for its simplicity. When I run my program with the input string "This is a test string with various characters!", I end up with a hash value of -1032675006 instead of a positive integer. I’m currently using GCC version 11.2.0 on Ubuntu 20.04. Is there a way to prevent this overflow, or should I switch to a different algorithm altogether? Any suggestions or insights would be greatly appreciated! I'm working on a mobile app that needs to handle this. Any pointers in the right direction? How would you solve this?