Why Does C# Throw 'An Object Reference Is Required for the Non-Static Field, Method, or Property'?

C# exception: "An object reference is required to access a non-static field, method, or property"

In C#, the "Object reference is required to access a non-static field, method, or property" error usually occurs when a static method tries to access a non-static member of the class.

The error in this article occurs in the following line of code in the Main method:

<code class="language-c#">Population[i].bits = GetRandomBits();</code>

The problem is with the GetRandomBits method, which is declared as a non-static method in the Program class. However, the Main method is defined as a static method, which means it can only access static members of the class.

Solution

There are two ways to resolve this error:

1. Create an instance of the class:

Static methods cannot directly access non-static members. To access a non-static method or property from a static method, you first create an instance of the class and then call the method or access the property through that instance. For example:

<code class="language-c#">// 创建 Program 类的实例
Program p = new Program();

// 通过实例调用 GetRandomBits 方法
Population[i].bits = p.GetRandomBits();</code>

2. Make the method static:

Alternatively, you can make it a static method by adding the Program keyword when declaring the GetRandomBits method in the static class. This way, static Main methods can directly access the GetRandomBits method without creating an instance. For example:

<code class="language-c#">public static string GetRandomBits()
{
    // 方法实现
}</code>

With either of the above methods, you can eliminate the error and make the Main method correctly access the GetRandomBits method.

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