Rule Definition
When placed in a loop, String concatenation results in the creation and garbage collection of large numbers of temporary objects. This both consumes memory and can dramatically slow the program execution. It is recommended to create a StringBuilder before entering the loop, and append to it within the loop, thus reducing the overhead.

Remediation
It is recommended to create a StringBuilder before entering the loop, and append to it within the loop, thus reducing the overhead.

Violation Code Sample

static void LoopKO()
      {
         String myText = "hello" ;
         for(int i = 0; i < 1000; i++)
         {
            myText += "count =";        // VIOLATION
            myText += i.ToString();     // VIOLATION
         }
         Console.WriteLine(myText.ToString());
      }

Fixed Code Sample

static void LoopOK()
      {
         StringBuilder myText = new StringBuilder();
         for(int i = 0; i < 1000; i++)
         {
            myText.Append("count =");       // FIXED
            myText.Append(i.ToString());      // FIXED
         }
         Console.WriteLine(myText.ToString());
      }

CISQ rule: ASCPEM-PRF-2.