If a local variable is declared but not used, it is dead code and should be removed. Doing so will improve maintainability because developers will not wonder what the variable is used for.

Noncompliant Code Example

public int NumberOfMinutes(int hours)
{
  int seconds = 0;   // seconds is never used
  return hours * 60;
}

Compliant Solution

public int NumberOfMinutes(int hours)
{
  return hours * 60;
}

Exceptions

Unused locally created resources in a using statement are not reported.

using(var t = new TestTimer()) // t never used, but compliant.
{
  //...
}