title: unable to convert int to string in SSIS expression
body: <p>hi i'm using below expression for filename with datetime stamp.</p>
  
  <pre><code>(DT_I4)DATEPART("weekday", GETDATE() ) ==2  || (DT_I4)DATEPART("weekday",@[System::StartTime]) ==7 ? 
  Replace((DT_STR, 20, 1252)(DATEADD( "D", -3,@[System::StartTime])),":","-") + ".xls" :
  Replace((DT_STR, 20, 1252)(DATEADD( "D", -1,@[System::StartTime])),":","-") + ".xls"
  </code></pre>
  
  <p>which will give me previous date always what is my need.</p>
  
  <p>but when i append filename to this expression it is giving me following error - </p>
  
  <pre><code>"FILENAME"+ 
   (DT_I4)DATEPART("weekday", GETDATE() ) ==2  || (DT_I4)DATEPART("weekday",@[System::StartTime]) ==7 ? 
      Replace((DT_STR, 20, 1252)(DATEADD( "D", -3,@[System::StartTime])),":","-") + ".xls" :
      Replace((DT_STR, 20, 1252)(DATEADD( "D", -1,@[System::StartTime])),":","-") + ".xls"
  </code></pre>
  
  <p>ERROR - 
  The data types "DT_WSTR" and "DT_I4" are incompatible for binary operator "+". The operand types could not be implicitly cast into compatible types for the operation. To perform this operation, one or both operands need to be explicitly cast with a cast operator.</p>
  
  <p>Attempt to set the result type of binary operation "@[User::AnimalName] + (DT_I4)DATEPART("weekday",@[System::StartTime])" failed with error code 0xC0047080.</p>
  
  <p>(Microsoft.DataTransformationServices.Controls)</p>