C＃String.IsNullOrEmpty()方法 (C# String.IsNullOrEmpty() Method)

String.IsNullOrEmpty() method is a built-in method of String class and it is used to check whether a string is Null or Empty? If string object is not initialized with a correct value it will be considered as "null string", if string object is initialized but contains nothing i.e. it is assigned the value ("") it will be considered as "empty string".

String.IsNullOrEmpty()方法是String類的內置方法，用于檢查字符串是Null還是Empty ？ 如果未使用正確的值初始化字符串對象，則將其視為“空字符串” ；如果已初始化字符串對象但不包含任何值，即為該字符串對象分配了值( “” )，則將其視為“空字符串” 。

Syntax:

句法：

public static bool IsNullOrEmpty(String str);

The method is called with "string"/ "String". Here, "string" is an alias of "String" class.

用“字符串” /“字符串”調用該方法。 此處，“字符串”是“字符串”類的別名。

Parameter(s):

參數：

• str – represents a string value or string object to be checked.

  str –表示要檢查的字符串值或字符串對象。

Return value:

返回值：

• bool – it returns "True" if str is null or empty, otherwise it returns "False".

  bool-如果str為null或為空，則返回“ True”，否則返回“ False”。

Example:

例：

Input:string str1 = "";string str2 = null;string str3 = "IncludeHelp";Function callConsole.WriteLine(string.IsNullOrEmpty(str1));Console.WriteLine(string.IsNullOrEmpty(str2));Console.WriteLine(string.IsNullOrEmpty(str3));Output:TrueTrueFalse

C＃使用String.IsNullOrEmpty()方法將字符串轉換為字符數組的示例 (C# Example to convert string to characters array using String.IsNullOrEmpty() method)

Example 1:

范例1：

using System; class IncludeHelp {static void Main(){// declaring string variablesstring str1 = "";string str2 = null;string str3 = "IncludeHelp";// check whether string is empty/null or notConsole.WriteLine(string.IsNullOrEmpty(str1));Console.WriteLine(string.IsNullOrEmpty(str2));Console.WriteLine(string.IsNullOrEmpty(str3));} }

Output

輸出量

True True False

Example 2:

范例2：

using System;class IncludeHelp {static void Main(){// declaring string variablestring str = "IncludeHelp";// checking whether string is null/empty or notif(string.IsNullOrEmpty(str))Console.WriteLine("str is empty or null");elseConsole.WriteLine("str is not empty or null");//now assigning null to the stringstr = null;// checking whether string is null/empty or notif(string.IsNullOrEmpty(str))Console.WriteLine("str is empty or null");elseConsole.WriteLine("str is not empty or null");} }

Output

輸出量

str is not empty or null str is empty or null

翻譯自: https://www.includehelp.com/dot-net/string-isnullorempty-method-with-example-in-csharp.aspx

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