将值设置为基本类型的实例

发布于 2024-09-05 20:11:06 字数 459 浏览 4 评论 0原文

我有一个执行某些操作的函数，即从数据库中获取一些数据。它采用的泛型始终是原始类型，即 int、char、bool、string 等。我可以轻松创建它的实例。但我无法将从数据库获取的值设置到此实例。

public T PerformOperation<T>()
{    
    object instance = (T)Activator.CreateInstance(typeof(T));

    object result=FetchData();

    instance = (T)result; //It gives error on this statement
}

该函数被调用为：

int result = PerformOperation<int>();

是否有某种方法将对象类型转换为任何始终是原始类型的泛型类型？

原文

I have a function which performs some operation i.e. fetches some data from database.
The generic it takes is primitive type always i.e. int, char, bool, string etc. I can easily create its instance. But I can't set the value that I have fetched from database to this instance.

public T PerformOperation<T>()
{    
    object instance = (T)Activator.CreateInstance(typeof(T));

    object result=FetchData();

    instance = (T)result; //It gives error on this statement
}

The function is called as:

int result = PerformOperation<int>();

Is there some way of casting the object Type to any generic type which is always primitive?

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时光暖心i 2024-09-12 20:11:06

当您已经拥有类型 T 时，为什么不需要将其装箱到 Object 中。

public T PerformOperation<T>()
{    
    T instance = (T)Activator.CreateInstance(typeof(T)); // why do you need this ?

    T result = FetchData();

    //instance = (T)result;
    return result;
}

或者如果您必须使用Object，则可能是这种方式。

public T PerformOperation<T>()
{    
    //object instance = (T)Activator.CreateInstance(typeof(T));    
    //object result=FetchData();

    return (T)FetchData(); // If I could get you correctly.
}

When you already have type T, why box it into Object unnecessary.

public T PerformOperation<T>()
{    
    T instance = (T)Activator.CreateInstance(typeof(T)); // why do you need this ?

    T result = FetchData();

    //instance = (T)result;
    return result;
}

or may be this way, if you must use Object.

public T PerformOperation<T>()
{    
    //object instance = (T)Activator.CreateInstance(typeof(T));    
    //object result=FetchData();

    return (T)FetchData(); // If I could get you correctly.
}

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