While exceptions have always existed in C# the throw keyword was only treated as a statement which meant it could not be used in places where only expressions were allowed such as inside a conditional or coalescing operator.

C# 7.0 introduces throw expressions which allow exceptions to be thrown in more convenient ways.

Code

Now

void ProcessAdult(string name, age)
{
    var requiredName = name ?? throw new ArgumentNullException(nameof(name));
    var adultAge = age >= 18 ? age : throw new ArgumentOutOfRangeException(nameof(age));

    // ...
}

Before

void ProcessAdult(string name, age)
{
    if (name == null)
    {
        throw new ArgumentNullException(nameof(name));
    }
    var requiredName = name;

    if (age < 18)
    {
        throw new ArgumentOutOfRangeException(nameof(age));
    }
    var adultAge = age;

    // ...
}

More information

• What's new in C# 7.0