CODEWITHSUNDEEP
c#functionparameters
Craig Schwarze
Craig Schwarze

Reputation: 11625

Pass multiple optional parameters to a C# function

Is there a way to set up a C# function to accept any number of parameters? For example, could you set up a function such that the following all work - 

x = AddUp(2, 3)

x = AddUp(5, 7, 8, 2)

x = AddUp(43, 545, 23, 656, 23, 64, 234, 44)

Upvotes: 89

Views: 148213

Answers (3)

Tarydon
Tarydon

Reputation: 5183

C# 4.0 also supports optional parameters, which could be useful in some other situations. See this article.

Upvotes: 7

Pit J
Pit J

Reputation: 179

1.You can make overload functions. 

SomeF(strin s){}   
SomeF(string s, string s2){}    
SomeF(string s1, string s2, string s3){}

More info: http://csharpindepth.com/Articles/General/Overloading.aspx

2.or you may create one function with params

SomeF( params string[] paramArray){}
SomeF("aa","bb", "cc", "dd", "ff"); // pass as many as you like

More info: https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/params

3.or you can use simple array

Main(string[] args){}

Upvotes: 5

Jon Skeet
Jon Skeet

Reputation: 1500675

Use a parameter array with the params modifier:

public static int AddUp(params int[] values)
{
    int sum = 0;
    foreach (int value in values)
    {
        sum += value;
    }
    return sum;
}

If you want to make sure there's at least one value (rather than a possibly empty array) then specify that separately:

public static int AddUp(int firstValue, params int[] values)

(Set sum to firstValue to start with in the implementation.)

Note that you should also check the array reference for nullity in the normal way. Within the method, the parameter is a perfectly ordinary array. The parameter array modifier only makes a difference when you call the method. Basically the compiler turns:

int x = AddUp(4, 5, 6);

into something like:

int[] tmp = new int[] { 4, 5, 6 };
int x = AddUp(tmp);

You can call it with a perfectly normal array though - so the latter syntax is valid in source code as well.

Upvotes: 189

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