Is possible to create method with dynamic number of parameter in C#?
For example
Public void sum(dynamic arguments//like JavaScript)
{
//loop at run-time on arguments and sum
}
Can I use Dynamic Object?
3 Answers
Use the params keyword to achieve a variable number of arguments.
The params keyword lets you specify a method parameter that takes a variable number of arguments. You can send a comma-separated list of arguments of the type specified in the parameter declaration, or an array of arguments of the specified type. You also can send no arguments.
For example: public void Sum( params int[] args ){ }
Can I use Dynamic Object?
Yes, but possibly not in the way you are thinking.
// example 1 - single parameter of type dynamic
private static void Sum( dynamic args ) { }
// will not compile; Sum() expects a single parameter whose type is not
// known until runtime
Sum( 1, 2, 3, 4, 5 );
// example 2 - variable number of dynamically typed arguments
private static void Sum( params dynamic[] args ) { }
// will compile
Sum( 1, 2, 3, 4, 5 );
So you could have a method such as:
public static dynamic Sum( params dynamic[] args ) {
dynamic sum = 0;
foreach( var arg in args ){
sum += arg;
}
return sum;
}
And call it: Sum( 1, 2, 3, 4.5, 5 ). The DLR is smart enough to infer the correct type from the arguments, and the returned value will be System.Double. However (at least in the case of a Sum() method), giving up explicit control over type specification and losing type safety seems like a bad idea.
I'm assuming you have a reason for not using Enumerable.Sum()
yes, you can take a look here
http://msdn.microsoft.com/library/w5zay9db(v=vs.80).aspx
(the params keyword)
Comments
Maybe an example unit test clarifies things slightly:
[Test]
public void SumDynamics()
{
// note that we can specify as many ints as we like
Assert.AreEqual(8, Sum(3, 5)); // test passes
Assert.AreEqual(4, Sum(1, 1 , 1, 1)); // test passes
Assert.AreEqual(3, Sum(3)); // test passes
}
// Meaningless example but it's purpose is only to show that you can use dynamic
// as a parameter, and that you also can combine it with the params type.
public static dynamic Sum(params dynamic[] ints)
{
return ints.Sum(i => i);
}
Be aware when using dynamics, you are telling your compiler to back off, so you will get your exceptions at run-time.
[Test, ExpectedException(typeof(RuntimeBinderException))]
public void AssignDynamicIntAndStoreAsString()
{
dynamic i = 5;
string astring = i; // this will compile, but will throw a runtime exception
}
Read more about dynamics.
Read more about params
params? bla(params int[] variableInts)dynamictype as parameter? and could you update your question accordingly, kinda vague atm.