[英]How to skip optional parameters in C#?
Example: 例:
public int foo(int x, int optionalY = 1, int optionalZ = 2) { ... }
I'd like to call it like this: 我想这样称呼它:
int returnVal = foo(5,,8);
In other words, I want to provide x
and z
, but I want to use the default for Y
, optionalY = 1.
换句话说,我想提供x
和z
,但我想使用Y
的默认值, optionalY = 1.
Visual Studio does not like the ,,
Visual Studio不喜欢,,
Please help. 请帮忙。
In C# 4.0 you can name the arguments occurring after skipped defaults like this: 在C#4.0中,您可以命名在跳过默认值之后发生的参数,如下所示:
int returnVal = foo(5, optionalZ: 8);
This is called as named arguments . 这称为命名参数 。 Several others languages provide this feature, and it's common form them to use the syntax foo(5, optionalZ=8)
instead, which is useful to know when reading code in other languages. 其他几种语言提供了这一功能,并且通常使用语法foo(5, optionalZ=8)
代替它,这对于了解何时阅读其他语言的代码很有用。
Another dynamic way to supply parameters of your choise is to implement your method(s) in a class and supply named parameters to the class constructor. 另一种提供选择参数的动态方法是在类中实现方法,并为类构造函数提供命名参数。 Why not even add calls to methods on same line of code as mentioned here : How to define named Parameters C# 为什么不在这里提到的同一行代码上添加对方法的调用: 如何定义命名参数C#
var p = new PersonInfo { Name = "Peter", Age = 15 }.BuildPerson(); var p = new PersonInfo {Name =“Peter”,Age = 15} .BuildPerson();
This is a late answer, but for the people who get into this. 这是一个迟到的答案,但对于那些进入这个问题的人来说。 One could also use Overloads,that uses the same name as the method/function, but with a different set of parameters. 也可以使用Overloads,它使用与方法/函数相同的名称,但使用不同的参数集。
ea EA
int SummAll (int a=0, int b=1, int c=2)
{return a+b+c;}
int SumAll (int a=0;int c=10) //skipping B
{return a+c; }
This pattern equals how with intellicense we can browse through variations of functions. 这种模式等同于我们可以浏览函数变体的intellicense。
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