uCalc API Version: 5.7.0-preview.1 Released: 7/30/2026

Warning

uCalc API Preview Release Notice:This preview documentation describes the intended behavior of the API. It is not fully accurate or complete.The current preview build contains incomplete features, unoptimized performance, and is subject to breaking changes.Use of the preview version in your production code is not recommended.

Error = [ErrorInfo]

Property

Product: 

Fast Math Parser

Class: 

Callback

Remarks

Examples

Raises an error in a callback using a customized message with ErrorRaiseMessage

ID: 39

See: Error = [ErrorInfo], Raise(string) 
				
					using uCalcSoftware;

var uc = new uCalc();

static void RaiseErrorMessageCallback(uCalc.Callback cb) {
   if (cb.Arg(1) == 123) {
      cb.Error.Raise("I do not like this value!");
      cb.Return(cb.Arg(1));
   }
}


uc.DefineFunction("ErrRaiseMsgTest(Value)", RaiseErrorMessageCallback);
Console.WriteLine(uc.EvalStr("ErrRaiseMsgTest(111)"));
Console.WriteLine(uc.EvalStr("ErrRaiseMsgTest(123)"));
				
			
111
I do not like this value!
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					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

void ucalc_call RaiseErrorMessageCallback(uCalcBase::Callback cb) {
   if (cb.Arg(1) == 123) {
      cb.Error().Raise("I do not like this value!");
      cb.Return(cb.Arg(1));
   }
}
int main() {
   uCalc uc;

   uc.DefineFunction("ErrRaiseMsgTest(Value)", RaiseErrorMessageCallback);
   cout << uc.EvalStr("ErrRaiseMsgTest(111)") << endl;
   cout << uc.EvalStr("ErrRaiseMsgTest(123)") << endl;
}
				
			
111
I do not like this value!
Explore 600+ other examples
				
					Imports System
Imports uCalcSoftware
Public Module Program
   
   Public Sub RaiseErrorMessageCallback(ByVal cb As uCalc.Callback)
      If cb.Arg(1) = 123 Then
         cb.Error.Raise("I do not like this value!")
         cb.Return(cb.Arg(1))
      End If
   End Sub
   Public Sub Main()
      Dim uc As New uCalc()
      
      uc.DefineFunction("ErrRaiseMsgTest(Value)", AddressOf RaiseErrorMessageCallback)
      Console.WriteLine(uc.EvalStr("ErrRaiseMsgTest(111)"))
      Console.WriteLine(uc.EvalStr("ErrRaiseMsgTest(123)"))
   End Sub
End Module
				
			
111
I do not like this value!
Explore 600+ other examples
A function that unconditionally raises a custom error.

ID: 482

See: Error = [ErrorInfo], Error = [ErrorInfo], Raise(string) 
				
					using uCalcSoftware;

var uc = new uCalc();

static void MyHandler(Handle_uCalc h) {
   var uc = new uCalc(h);
   // This handler just logs the error and aborts
   Console.WriteLine($"Error Handler Caught: {uc.Error.Message}");
}
static void MyFunc(uCalc.Callback cb) {
   // This function always fails with a custom message
   cb.Error.Raise("Validation failed for input.");
}

uc.Error.AddHandler(MyHandler);
uc.DefineFunction("Validate()", MyFunc);
uc.EvalStr("Validate()"); // This call will trigger the error
				
			
Error Handler Caught: Validation failed for input.
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					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

void ucalc_call MyHandler(Handle_uCalc h) {
   auto uc = uCalc(h);
   // This handler just logs the error and aborts
   cout << "Error Handler Caught: " << uc.Error().Message() << endl;
}
void ucalc_call MyFunc(uCalcBase::Callback cb) {
   // This function always fails with a custom message
   cb.Error().Raise("Validation failed for input.");
}
int main() {
   uCalc uc;
   uc.Error().AddHandler(MyHandler);
   uc.DefineFunction("Validate()", MyFunc);
   uc.EvalStr("Validate()"); // This call will trigger the error
}
				
			
Error Handler Caught: Validation failed for input.
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					Imports System
Imports uCalcSoftware
Public Module Program
   
   Public Sub MyHandler(ByVal h As Handle_uCalc)
      Dim uc As New uCalc(h)
      '// This handler just logs the error and aborts
      Console.WriteLine($"Error Handler Caught: {uc.Error.Message}")
   End Sub
   Public Sub MyFunc(ByVal cb As uCalc.Callback)
      '// This function always fails with a custom message
      cb.Error.Raise("Validation failed for input.")
   End Sub
   Public Sub Main()
      Dim uc As New uCalc()
      uc.Error.AddHandler(AddressOf MyHandler)
      uc.DefineFunction("Validate()", AddressOf MyFunc)
      uc.EvalStr("Validate()") '// This call will trigger the error
   End Sub
End Module
				
			
Error Handler Caught: Validation failed for input.
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Raises an error with a dynamic message if a validation check fails within a callback.

ID: 483

See: Error = [ErrorInfo], Error handling and control flow, Raise(string) 
				
					using uCalcSoftware;

var uc = new uCalc();

static void ValidateValue(uCalc.Callback cb) {
   var val = cb.Arg(1);
   if (val > 100) {
      // The error message includes the problematic value, making it dynamic.
      cb.Error.Raise("Value exceeds maximum of 100. Got: " + val.ToString());
   } else {
      cb.Return(val);
   }
}

uc.DefineFunction("CheckValue(val)", ValidateValue);
Console.WriteLine(uc.EvalStr("CheckValue(50)"));
Console.WriteLine(uc.EvalStr("CheckValue(123)"));
				
			
50
Value exceeds maximum of 100. Got: 123
Explore 600+ other examples
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

void ucalc_call ValidateValue(uCalcBase::Callback cb) {
   auto val = cb.Arg(1);
   if (val > 100) {
      // The error message includes the problematic value, making it dynamic.
      cb.Error().Raise("Value exceeds maximum of 100. Got: " + to_string((int)val));
   } else {
      cb.Return(val);
   }
}
int main() {
   uCalc uc;
   uc.DefineFunction("CheckValue(val)", ValidateValue);
   cout << uc.EvalStr("CheckValue(50)") << endl;
   cout << uc.EvalStr("CheckValue(123)") << endl;
}
				
			
50
Value exceeds maximum of 100. Got: 123
Explore 600+ other examples
				
					Imports System
Imports uCalcSoftware
Public Module Program
   
   Public Sub ValidateValue(ByVal cb As uCalc.Callback)
      Dim val = cb.Arg(1)
      If val > 100 Then
         '// The error message includes the problematic value, making it dynamic.
         cb.Error.Raise("Value exceeds maximum of 100. Got: " + val.ToString())
      Else
         cb.Return(val)
      End If
   End Sub
   Public Sub Main()
      Dim uc As New uCalc()
      uc.DefineFunction("CheckValue(val)", AddressOf ValidateValue)
      Console.WriteLine(uc.EvalStr("CheckValue(50)"))
      Console.WriteLine(uc.EvalStr("CheckValue(123)"))
   End Sub
End Module
				
			
50
Value exceeds maximum of 100. Got: 123
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Internal Test: Demonstrates error recovery by having an error handler resume execution after a custom error is raised.

ID: 484

See: Error = [ErrorInfo], Raise(string) 
				
					using uCalcSoftware;

var uc = new uCalc();

static void RecoveryHandler(Handle_uCalc h) {
   var uc = new uCalc(h);
   Console.WriteLine($"Handler: Caught '{uc.Error.Message}'");
   // Attempt to recover by resuming execution.
   uc.Error.Response = ErrorHandlerResponse.Resume;
   Console.WriteLine("Handler: Resuming execution...");
}
static void RiskyOperation(uCalc.Callback cb) {
   var input = cb.ArgStr(1);
   if (input == "bad") {
      cb.Error.Raise("A recoverable error occurred.");
      // After the error handler resumes, this return value will be used.

   } else {
      cb.ReturnStr("Normal_OK");
   }
}

uc.Error.AddHandler(RecoveryHandler);
uc.DefineFunction("DoWork(s As String) As String", RiskyOperation);

Console.WriteLine("Result: " + uc.EvalStr("DoWork('good')"));
Console.WriteLine("---");
Console.WriteLine("Result: " + uc.EvalStr("DoWork('bad')"));
				
			
Result: Normal_OK
---
Handler: Caught 'A recoverable error occurred.'
Handler: Resuming execution...
Result: A recoverable error occurred.
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					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

void ucalc_call RecoveryHandler(Handle_uCalc h) {
   auto uc = uCalc(h);
   cout << "Handler: Caught '" << uc.Error().Message() << "'" << endl;
   // Attempt to recover by resuming execution.
   uc.Error().Response(ErrorHandlerResponse::Resume);
   cout << "Handler: Resuming execution..." << endl;
}
void ucalc_call RiskyOperation(uCalcBase::Callback cb) {
   auto input = cb.ArgStr(1);
   if (input == "bad") {
      cb.Error().Raise("A recoverable error occurred.");
      // After the error handler resumes, this return value will be used.

   } else {
      cb.ReturnStr("Normal_OK");
   }
}
int main() {
   uCalc uc;
   uc.Error().AddHandler(RecoveryHandler);
   uc.DefineFunction("DoWork(s As String) As String", RiskyOperation);

   cout << "Result: " + uc.EvalStr("DoWork('good')") << endl;
   cout << "---" << endl;
   cout << "Result: " + uc.EvalStr("DoWork('bad')") << endl;
}
				
			
Result: Normal_OK
---
Handler: Caught 'A recoverable error occurred.'
Handler: Resuming execution...
Result: A recoverable error occurred.
Explore 600+ other examples
				
					Imports System
Imports uCalcSoftware
Public Module Program
   
   Public Sub RecoveryHandler(ByVal h As Handle_uCalc)
      Dim uc As New uCalc(h)
      Console.WriteLine($"Handler: Caught '{uc.Error.Message}'")
      '// Attempt to recover by resuming execution.
      uc.Error.Response = ErrorHandlerResponse.Resume
      Console.WriteLine("Handler: Resuming execution...")
   End Sub
   Public Sub RiskyOperation(ByVal cb As uCalc.Callback)
      Dim input = cb.ArgStr(1)
      If input = "bad" Then
         cb.Error.Raise("A recoverable error occurred.")
         '// After the error handler resumes, this return value will be used.
         
      Else
         cb.ReturnStr("Normal_OK")
      End If
   End Sub
   Public Sub Main()
      Dim uc As New uCalc()
      uc.Error.AddHandler(AddressOf RecoveryHandler)
      uc.DefineFunction("DoWork(s As String) As String", AddressOf RiskyOperation)
      
      Console.WriteLine("Result: " + uc.EvalStr("DoWork('good')"))
      Console.WriteLine("---")
      Console.WriteLine("Result: " + uc.EvalStr("DoWork('bad')"))
   End Sub
End Module
				
			
Result: Normal_OK
---
Handler: Caught 'A recoverable error occurred.'
Handler: Resuming execution...
Result: A recoverable error occurred.
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Triggering a standard syntax error if the input value is negative.

ID: 479

See: Error = [ErrorInfo], Raise(ErrorCode) 
				
					using uCalcSoftware;

var uc = new uCalc();

static void DoublePositive(uCalc.Callback cb) {
   // If input is negative, raise a syntax error.
   if (cb.Arg(1) < 0) {
      cb.Error.Raise(ErrorCode.Syntax_Error);
   }
   cb.Return(cb.Arg(1) * 2);
}

uc.DefineFunction("DoublePositive(x)", DoublePositive);
Console.WriteLine(uc.EvalStr("DoublePositive(10)"));
Console.WriteLine(uc.EvalStr("DoublePositive(-5)"));
				
			
20
Syntax error
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					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

void ucalc_call DoublePositive(uCalcBase::Callback cb) {
   // If input is negative, raise a syntax error.
   if (cb.Arg(1) < 0) {
      cb.Error().Raise(ErrorCode::Syntax_Error);
   }
   cb.Return(cb.Arg(1) * 2);
}
int main() {
   uCalc uc;
   uc.DefineFunction("DoublePositive(x)", DoublePositive);
   cout << uc.EvalStr("DoublePositive(10)") << endl;
   cout << uc.EvalStr("DoublePositive(-5)") << endl;
}
				
			
20
Syntax error
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					Imports System
Imports uCalcSoftware
Public Module Program
   
   Public Sub DoublePositive(ByVal cb As uCalc.Callback)
      '// If input is negative, raise a syntax error.
      If cb.Arg(1) < 0 Then
         cb.Error.Raise(ErrorCode.Syntax_Error)
      End If
      cb.Return(cb.Arg(1) * 2)
   End Sub
   Public Sub Main()
      Dim uc As New uCalc()
      uc.DefineFunction("DoublePositive(x)", AddressOf DoublePositive)
      Console.WriteLine(uc.EvalStr("DoublePositive(10)"))
      Console.WriteLine(uc.EvalStr("DoublePositive(-5)"))
   End Sub
End Module
				
			
20
Syntax error
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Raising an error in a callback with ErrorRaise

ID: 37

See: Error = [ErrorInfo], Raise(ErrorCode) 
				
					using uCalcSoftware;

var uc = new uCalc();

static void RaiseErrorCallback(uCalc.Callback cb) {
   if (cb.Arg(1) == 123) {
      cb.Error.Raise(ErrorCode.Unrecognized_Command);
   }
   cb.Return(cb.Arg(1));
}


uc.DefineFunction("ErrRaiseTest(Value)", RaiseErrorCallback);
Console.WriteLine(uc.EvalStr("ErrRaiseTest(111)"));
Console.WriteLine(uc.EvalStr("ErrRaiseTest(123)")); // The callback arbitrarily raises an error for 123
				
			
111
Unrecognized command
Explore 600+ other examples
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

void ucalc_call RaiseErrorCallback(uCalcBase::Callback cb) {
   if (cb.Arg(1) == 123) {
      cb.Error().Raise(ErrorCode::Unrecognized_Command);
   }
   cb.Return(cb.Arg(1));
}
int main() {
   uCalc uc;

   uc.DefineFunction("ErrRaiseTest(Value)", RaiseErrorCallback);
   cout << uc.EvalStr("ErrRaiseTest(111)") << endl;
   cout << uc.EvalStr("ErrRaiseTest(123)") << endl; // The callback arbitrarily raises an error for 123
}
				
			
111
Unrecognized command
Explore 600+ other examples
				
					Imports System
Imports uCalcSoftware
Public Module Program
   
   Public Sub RaiseErrorCallback(ByVal cb As uCalc.Callback)
      If cb.Arg(1) = 123 Then
         cb.Error.Raise(ErrorCode.Unrecognized_Command)
      End If
      cb.Return(cb.Arg(1))
   End Sub
   Public Sub Main()
      Dim uc As New uCalc()
      
      uc.DefineFunction("ErrRaiseTest(Value)", AddressOf RaiseErrorCallback)
      Console.WriteLine(uc.EvalStr("ErrRaiseTest(111)"))
      Console.WriteLine(uc.EvalStr("ErrRaiseTest(123)")) '// The callback arbitrarily raises an error for 123
   End Sub
End Module
				
			
111
Unrecognized command
Explore 600+ other examples