可空类型Nullable<T>的四则运算原理

源代码

    int? a = 1;
    int? b = null;
    var jia = a + b;
    var jian = a - b;
    var cheng = a * b;
    var chu = a / b;

编译后用软件反编译 成 C# 1.0

    int? a = 1;
    int? b = null;
    int? nullable = a;
    int? nullable2 = b;
    int? jia = (nullable.HasValue & nullable2.HasValue) ? new int?(nullable.GetValueOrDefault() + nullable2.GetValueOrDefault()) : null;
    nullable2 = a;
    nullable = b;
    int? jian = (nullable2.HasValue & nullable.HasValue) ? new int?(nullable2.GetValueOrDefault() - nullable.GetValueOrDefault()) : null;
    nullable = a;
    nullable2 = b;
    int? cheng = (nullable.HasValue & nullable2.HasValue) ? new int?(nullable.GetValueOrDefault() * nullable2.GetValueOrDefault()) : null;
    nullable2 = a;
    nullable = b;
    int? chu = (nullable2.HasValue & nullable.HasValue) ? new int?(nullable2.GetValueOrDefault() / nullable.GetValueOrDefault()) : null;