I remember finding it super tricky to understand how to convert this hash table information to C code. There is a lot of confusion and trickiness when it comes to implementing hash tables in C, so I figured why not write about it! And trust me, once you get the idea, it becomes soooo interesting!!! You can also implement the Hash Table in C++ as well, with different classes. 1. hash functionSo first, we need to write a function to figure out where to place the key in the hash table. In this case lets say we have 10 slots in our hash table. The hash function can vary based on the formula of your choice, or the data type you are dealing with. What if we are trying to store char or string type keys? Hash Function
2. chainingThe next step of implementing hashing in C is to implement chaining. For this, we need to make a linked list. One way is to declare a Node structure with two variables: the value and the next Node. When we implement chaining in C, we must first decide how we are going to pass in the arguments. The insert function below takes in two parameters: Node **, which is a pointer to a Node pointer, and int el, which is the element to be inserted into the Hash Table. For this implementation in C, I'll be passing in the address of the slot in the Hash Table (based on the index). So if we are inserting the element 5, we will first do 5 % n to find the index, and then pass in the address of (&Hash[index]), which is a pointer to a node pointer. NOTE: the '&' is used in C as syntax for the address of something. In this case, H, which is a pointer to a Node pointer, is the address of the first slot in the Hash Table. *H, which is dereferenced, is the address of the Node (which is in the slot). And in this example we are just focusing on the index 0 of the hash table. 3. putting it all togetherSo now, we obviously have to put it all together using a common main function to access the above functions. (chaining and indexing- using the hash function!)
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2/28/2024 07:25:33 am
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