Question

    public ClassType(string type) {
        Type = type;
    }
    public ClassType(string type,bool isArray=false) {
        Type = type;
        IsArray = isArray;
    }


    ClassType ct = new ClassType("adsf");

Which constructor is chosen?

Answer 1

The overload that doesn’t require an optional parameter. Note that it’s just a “yes” or “no” decision here: “no optional parameters filled in automatically” is preferable to “some optional parameters filled in automatically” but there’s no preference between 1 or 2 being filled in. (That would be ambiguous.)

From section 7.5.3.2 of the C# 4 spec:

Otherwise if all parameters of M_P have
a corresponding argument whereas
default arguments need to be
substituted for at least one optional
parameter in M_Q then M_P is better than
M_Q.