How big should be “nonce” be in a blockchain?

I am attempting to create my own blockchain, in order to understand how they work. I wanted to know how big the nonce should be (e.g. 8 digits or something like that). I am using a PoW (proof-of-work) algorithm in my blockchain. This blockchain uses the SHA256 hashing algorithm.

I am using the C programming language in order to implement this blockchain.

Here is what the block looks like in code:

struct Block
{
    /*Block structure*/
    char* hash;
    char* prev_hash;
    char* from;
    char* to;
    long long int nonce;
    double amount;
    time_t timestamp;
};

#c #blockchain #cryptocurrency