Internal Test: A custom `IIf` implementation using `ByExpr` to test lazy evaluation. The branches containing division by zero are never executed, preventing errors.

ID: 1188

See: Creating Custom Functions 
				
					using uCalcSoftware;

var uc = new uCalc();

static void CustomIIf(uCalc.Callback cb) {
   bool condition = cb.ArgBool(1);
   var truePart = cb.ArgExpr(2);
   var falsePart = cb.ArgExpr(3);

   if (condition) {
      cb.Return(truePart.Evaluate());
   } else {
      cb.Return(falsePart.Evaluate());
   }
}

uc.DefineFunction("MyIIf(condition As Bool, ByExpr thenExpr, ByExpr elseExpr)", CustomIIf);

// The 'else' branch contains a division by zero, but it should NOT be evaluated
// because the condition (1 < 2) is true.
var result = uc.Eval("MyIIf(1 < 2, 100, 1/0)");
Console.Write("Result 1: ");
Console.WriteLine(result);

// Now test the false branch. The 'then' branch with the error is skipped.
result = uc.Eval("MyIIf(1 > 2, 1/0, 200)");
Console.Write("Result 2: ");
Console.WriteLine(result);
				
			
Result 1: 100
Result 2: 200
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					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

void ucalc_call CustomIIf(uCalcBase::Callback cb) {
   bool condition = cb.ArgBool(1);
   auto truePart = cb.ArgExpr(2);
   auto falsePart = cb.ArgExpr(3);

   if (condition) {
      cb.Return(truePart.Evaluate());
   } else {
      cb.Return(falsePart.Evaluate());
   }
}
int main() {
   uCalc uc;
   uc.DefineFunction("MyIIf(condition As Bool, ByExpr thenExpr, ByExpr elseExpr)", CustomIIf);

   // The 'else' branch contains a division by zero, but it should NOT be evaluated
   // because the condition (1 < 2) is true.
   auto result = uc.Eval("MyIIf(1 < 2, 100, 1/0)");
   cout << "Result 1: ";
   cout << result << endl;

   // Now test the false branch. The 'then' branch with the error is skipped.
   result = uc.Eval("MyIIf(1 > 2, 1/0, 200)");
   cout << "Result 2: ";
   cout << result << endl;
}
				
			
Result 1: 100
Result 2: 200
Explore 600+ other examples
				
					Imports System
Imports uCalcSoftware
Public Module Program
   
   Public Sub CustomIIf(ByVal cb As uCalc.Callback)
      Dim condition As Boolean = cb.ArgBool(1)
      Dim truePart = cb.ArgExpr(2)
      Dim falsePart = cb.ArgExpr(3)
      
      If condition Then
         cb.Return(truePart.Evaluate())
      Else
         cb.Return(falsePart.Evaluate())
      End If
   End Sub
   Public Sub Main()
      Dim uc As New uCalc()
      uc.DefineFunction("MyIIf(condition As Bool, ByExpr thenExpr, ByExpr elseExpr)", AddressOf CustomIIf)
      
      '// The 'else' branch contains a division by zero, but it should NOT be evaluated
      '// because the condition (1 < 2) is true.
      Dim result = uc.Eval("MyIIf(1 < 2, 100, 1/0)")
      Console.Write("Result 1: ")
      Console.WriteLine(result)
      
      '// Now test the false branch. The 'then' branch with the error is skipped.
      result = uc.Eval("MyIIf(1 > 2, 1/0, 200)")
      Console.Write("Result 2: ")
      Console.WriteLine(result)
   End Sub
End Module
				
			
Result 1: 100
Result 2: 200
Explore 600+ other examples