ruby hash方法

Hash.rehash方法 (Hash.rehash Method)

In this article, we will study about Hash.rehash Method. The working of the method can't be assumed because of it's quite a different name. Let us read its definition and understand its implementation with the help of syntax and program codes.

在本文中，我們將研究Hash.rehash方法 。 由于該方法的名稱完全不同，因此無法進行假設。 讓我們閱讀其定義并在語法和程序代碼的幫助下了解其實現。

Method description:

方法說明：

This method is a Public instance method and belongs to the Hash class which lives inside the library of Ruby language. This method works in a way that constructs a new hash object which is based on the current hash object values for individual keys. If there is a change introduced in the hash object after they are declared then this method will do a re-indexing of the keys in the hash. You will have to face a run time error if you are trying to invoke this function during the process of traversing the hash instance.

此方法是Public實例方法，屬于Hash類，它位于Ruby語言庫中。 此方法以構造新哈希對象的方式工作，該對象基于單個鍵的當前哈希對象值。 如果聲明了哈希對象后引入了更改，則此方法將對哈希中的鍵進行重新索引。 如果在遍歷哈希實例的過程中嘗試調用此函數，則將面臨運行時錯誤。

Syntax:

句法：

Hash_object.rehash

Argument(s) required:

所需參數：

This method does not require any arguments.

此方法不需要任何參數。

Example 1:

范例1：

=beginRuby program to demonstrate Hash.rehash method =enda = ["Satyam","Amisha"] b = ["Nikhil","Saksham"]hsh = {a=>"friends", b=>"friends"}puts "Hash elements are: #{hsh}"puts "Hash.rehash implementation"b[0]="Hrithik"puts "Hash after rehash: #{hsh.rehash}"

Output

輸出量

Hash elements are: {["Satyam", "Amisha"]=>"friends", ["Nikhil", "Saksham"]=>"friends"} Hash.rehash implementation Hash after rehash: {["Satyam", "Amisha"]=>"friends", ["Hrithik", "Saksham"]=>"friends"}

Explanation:

說明：

In the above code, you can observe that you can rehash a hash object with the help of the Hash.rehash() method. We have inserted a new element inside the hash and replaced the current one. We got the result after rehashing the hash instance. This method is not creating changes in the original hash because this method is an example of non-destructive methods where the changes created by the method are not permanent.

在上面的代碼中，您可以觀察到可以借助Hash.rehash()方法重新哈希一個哈希對象。 我們在哈希表中插入了一個新元素，并替換了當前元素。 重新哈希哈希實例后，我們得到了結果。 此方法不會在原始哈希中創建更改，因為此方法是非破壞性方法的示例，在該示例中，該方法創建的更改不是永久的。

Example 2:

范例2：

=beginRuby program to demonstrate Hash.rehash method =enda = ["Satyam","Amisha"] b = ["Nikhil","Saksham"]hsh = {a=>"friends", b=>"friends"}puts "Hash elements are: #{hsh}"puts "Hash.rehash implementation"hsh.each do |key,value| hsh.rehash endputs "Hash after rehash: #{hsh.rehash}"

Output

輸出量

Hash elements are: {["Satyam", "Amisha"]=>"friends", ["Nikhil", "Saksham"]=>"friends"} Hash.rehash implementation rehash during iteration (repl):14:in `rehash' (repl):14:in `block in <main>' (repl):14:in `each' (repl):14:in `<main>'

Explanation:

說明：

In the above code, you can observe that when we are trying to rehash the hash instance during iteration then the method is throwing an exception named RuntimeError. This simply shows that you can’t rehash a hash during the process of iteration.

在上面的代碼中，您可以觀察到，當我們嘗試在迭代過程中重新哈希該哈希實例時，該方法將拋出一個名為RuntimeError的異常。 這僅表明您無法在迭代過程中重新哈希。

翻譯自: https://www.includehelp.com/ruby/hash-rehash-method-with-example.aspx

ruby hash方法

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