The size of the hash table is 10, and the key-value(item) is 48, then hash function = 43 % 10 = 3 therefore, the hash code will be 3, which means 43 items is placed in the hash table at the index 3. So to add some items inside the hash table, we need to have a hash function using the hash index of the given keys, and this has to be calculated using the hash function as “hash_inx = key % num_of_slots(size of the hash table) ” for, eg. In the above, we can see we have a syntax to write or create a hash class, and then we can create an object in std::hash class using the below syntax: The hash class can be defined using the STL library in C++, which is used for fetching the hash value of the parameters that are being passed to it, so let us see the syntax below: So in real-time, we can relate this hash function or hash table to a telephone directory book where each name is a key and the telephone number as a value to the key, which is the name. There is a chance of collision of two or more keys pointing to the same values and can be avoided by using chain hashing, which will point the linked list records as each cell in the hash table having the same have the same values that the hash key maps to the hash function values. In C++, the hash function is a function where a key is pointing to a value which is an address when this function is called, which uses the combination of letters and numbers in the hash table, which can be used for the arrangement of data. ![]() So the main moto of using a hash is to make the searching faster, which is done using the indexes of each value that are located in memory where a hash function has the key (index), which points to the address of the value that is located in the memory where it can be fetched faster by using its key. In this article, we will see the hash class defined as std::hash in the C++ standard library, which allows the user to create a hash class that can construct the objects without initializing the values and parameters can say a hash class as a template class. ![]() Working of the hash function in C++ with examples The standard library of C++ which provides a class called hash class which can be constructed without passing any arguments, so in general, a hash function is used for hashing, which will map key to some values which forms a hash table a data structure which this function will compute an index into an array. And if the hash function returns a unique hash number, then this hash function is called a universal hash function. When this function is called, it will generate an address for each key which is given in the hash function. ![]() In C++, the hash is a function that is used for creating a hash table.
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