Unused parameters are misleading. Whatever the values passed to such parameters, the behavior will be the same.

This rule raises an issue when a private method or constructor of a class/struct takes a parameter without using it.

Noncompliant Code Example

private void DoSomething(int a, int b) // "b" is unused
{
    Compute(a);
}

private void DoSomething2(int a) // value of "a" is unused
{
    a = 10;
    Compute(a);
}

Compliant Solution

private void DoSomething(int a)
{
    Compute(a);
}

private void DoSomething2()
{
    var a = 10;
    Compute(a);
}

Exceptions

This rule doesn’t raise any issue in the following contexts:

• The this parameter of extension methods.
• Methods decorated with attributes.
• Empty methods.
• Methods which only throw NotImplementedException.
• Main methods.
• virtual, override methods.
• interface implementations.