是否有可空值的加法赋值运算符的简写，如果为空则设置值? [英] Is there a shorthand for addition assignment operator for nullables that sets the value if null?

问题描述

我使用可空双精度来存储从各种来源提取的某些值的总和.如果不存在任何元素，则总和可以是任何实数值或 null.

I am using nullable doubles to store the sum of some values pulled from various sources. The sum could be any real value or null if no elements are present.

目前，我使用空检查并分配或递增:

Currently, I use a null check and either assign or increment:

double? sum = null;
...    
if(sum == null)
    sum = someTempValue;
else
    sum += someTempValue;

我知道 c# 有几个对方法调用等的速记空检查.我的问题是，当使用可空值时，如果 null 分配值或 not null?

I know c# has several shorthand null checks for method calls and the such. My question is if there is a shorthand notation to the addition assignment operator += when using nullables that assigns the value if null or performs the operation if not null?

推荐答案

你可以放三元运算符:

double? sum = null;
sum = sum == null ? someTempValue : sum + someTempValue;

或

sum = someTempValue + (sum == null ? 0 : sum);

或者

sum = someTempValue + (sum ?? 0);

归功于:Dmitry Bychenko 最后一个选项

Credit to: Dmitry Bychenko for the last option

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