title: C#, Operator '??' cannot be applied to operands of type 'decimal' and 'decimal'
body: <pre><code>public decimal v1 {
    get {
      return this._v1; 
    }
    set {
      this._v1 = value ?? 0M;  // also I tried, default(decimal)
    }
  }
  </code></pre>
  
  <p>Error message say : </p>
  
  <p><strong>Operator '??' cannot be applied to operands of type 'decimal' and 'decimal'</strong></p>
  
  <p>Why it does not work, and how should I do make it works?</p>