Yesterday I taught an intro to PowerBuilder .NET 12.5 session.  Part of the presentation had me comparing the.NET IL code inside an assemblies generated from code written in C# and PowerBuilder.

The C# code, after performing a simple arithmetic calculation echoed results to the console using these two lines of code

namespace CalculatorExample
{
class Program {
static void Main( )   {
Calc c = new Calc( );  //create the object
int ans = c.Add( 10, 84); //call the method
System.Console.WriteLine("10 + 84 is {0}." , ans);
System.Console.ReadLine( ) ;    }
}
class Calc {   //define a wrapper class for the method
public int Add( int x, int y)
{return x + y ; }  }
}

In PowerScript, ordinarily, I echo results using a Messagebox call, but yesterday, I thought I'd "step out on the limb" and echo output to the console using the same NET Framework class methods C# programmers use.

The equivalent PowerScript Code (slightly refactored) looks like this:

n_calc Calc
Calc = create n_calc
integer addend1=10, addend2=84, result
result = Calc.add( addend1, addend2 )
System.Console.WriteLine("{0} + {1} is {2}", addend1, addend2,result)
System.Console.ReadLine( )

I opened a console window and ran the app from the command line

The first run threw this exception:

Hmm, that's the ReadLine call.  I removed that line and ran it again

Hmm, no console output.  Then a clever programmer suggested that I pipe the output to a text file and then type the file.

Wow! Strange! What a trick! It worked! Here's the console output.  You can plainly see that we did get results, but for some reason they didn't display to the console device.  Only through outstream redirection was I able to capture the output.

I'd be mighty pleased if someone in engineering could explain this behavior.  Why can't a PB program directly write to the console in a displayable manner?   Why does ReadLine throw an exception?