PHP错误注意：哈希函数中的数组到字符串转换

我想使用PHP-OOP构建区块链

我的代码：

    class Block {

        public function __construct($timestamp, $transactions, $previousHash = null) {
            $this->previousHash = $previousHash;
            $this->timestamp = $timestamp;
            $this->transactions = $transactions;
            $this->nonce = 0;
            $this->hash = $this->calculateHash();
            $this->difficulty = 2;
        }

        /** Returns the SHA256 of this block (by processing all the data stored inside this block)*/
        public function calculateHash() {
            return hash("sha256", $this->previousHash.$this->timestamp.((string)$this->transactions).$this->nonce);
        }
      }

它向我显示了以下错误：

PHP Notice:  Array to string conversion in /home/istabraq/bctest/test2/a2.php on line 14

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有什么想法吗？

将数组转换为字符串可以使用函数：

        public function calculateHash() {
            return hash("sha256", $this->previousHash.$this->timestamp.(implode('', $this->transactions)).$this->nonce);
        }

string$this->transactions不会执行您期望的操作