使用具有一些空值的linq遍历数组

Question

I have an Array of Questions , some of them are null and some of them have something. like this :

Questions = {null , null , object , null , object}

Is the any way to use linq on this array ?

Questions.Where(x => x.someValue == OtherValue).ToList();

This gives me error

Thanks.

Answer 1

You are getting the error because you try to check for a property on a null object. Try this:

Questions.Where(x => (x != null) && (x.someValue == OtherValue)).ToList();

Like this, the compiler won't look into the 2nd condition ( x.someValue == OtherValue ) if the first condition is false.

Answer 2

You could filter out the null values first:

Questions
    .Where(x => x != null)
    .Where(x => x.someValue == OtherValue)
    .ToList();

Answer 3

您可以使用C＃6功能Null条件运算符

Questions.Where(x => x?.someValue == OtherValue).ToList();