CA2230: Use params for variable arguments


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A public or protected type contains a public or protected method that uses the VarArgs calling convention.

The VarArgs calling convention is used with certain method definitions that take a variable number of parameters. A method using the VarArgs calling convention is not Common Language Specification (CLS) compliant and might not be accessible across programming languages.

In C#, the VarArgs calling convention is used when a method's parameter list ends with the __arglist keyword. Visual Basic does not support the VarArgs calling convention, and Visual C++ allows its use only in unmanaged code that uses the ellipse ... notation.

To fix a violation of this rule in C#, use the params keyword instead of __arglist.

Do not suppress a warning from this rule.

The following example shows two methods, one that violates the rule and one that satisfies the rule.

using System;

[assembly: CLSCompliant(true)]
namespace UsageLibrary
    public class UseParams 
        // This method violates the rule.
        public void VariableArguments(__arglist) 
            ArgIterator argumentIterator = new ArgIterator(__arglist);
            for(int i = 0; i < argumentIterator.GetRemainingCount(); i++) 
                    __refvalue(argumentIterator.GetNextArg(), string));

        // This method satisfies the rule.
        public void VariableArguments(params string[] wordList)
            for(int i = 0; i < wordList.Length; i++) 

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