C# Error CS1575 – A stackalloc expression requires [] after type

C# Error

CS1575 – A stackalloc expression requires [] after type

Reason for the Error & Solution

A stackalloc expression requires [] after type

The size of the requested allocation, with , must be specified in square brackets.

The following sample generates CS1575:

// CS1575.cs  
// compile with: /unsafe  
public class MyClass  
{  
   unsafe public static void Main()  
   {  
      int *p = stackalloc int (30);   // CS1575  
      // try the following line instead  
      // int *p = stackalloc int [30];  
   }  
}