c# - 为什么在 C# 中引用和输出？

Question

当使用关键字ref时，调用代码需要初始化传递的参数，但是使用关键字out我们需要不要这样做。

• 为什么我们不到处使用 out？
• 两者的确切区别是什么？
• 请举例说明我们需要使用 ref 而不能使用 out 的情况？

Answer 1

这个MSDN article中给出了答案.来自那个帖子:

The two parameter passing modes addressed by out and ref are subtly different, however they are both very common. The subtle difference between these modes leads to some very common programming errors. These include:

1. not assigning a value to an out parameter in all control flow paths
2. not assigning a value to variable which is used as a ref parameter

Because the C# language assigns different definite assignment rules to these different parameter passing modes, these common coding errors are caught by the compiler as being incorrect C# code.

The crux of the decision to include both ref and out parameter passing modes was that allowing the compiler to detect these common coding errors was worth the additional complexity of having both ref and out parameter passing modes in the language.