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.

ReturnBool

Method

Product: 

Fast Math Parser

Class: 

Callback

Sets the boolean return value for a callback function.

Syntax

ReturnBool(bool)

Parameters

value
bool
The boolean value to be returned to the uCalc engine.

Return

void

This method does not return a value.

Remarks

The ReturnBool method is used within a callback function to send a boolean result back to the uCalc evaluation engine. It is the designated method for returning values from functions whose signatures are defined with As Bool.

When you create a custom function using DefineFunction and bind it to a native callback, the callback does not use a standard return statement to pass data back to uCalc. Instead, it uses the family of Return... methods on the uCalc.Callback object (cb). ReturnBool is the type-safe method for boolean values.

Type-Specific Returns

uCalc provides a specific return method for each primary data type to ensure type safety and clarity:

Using the correct method corresponding to the function's declared return type is crucial for predictable behavior.

💡 Comparative Analysis

In a native language like C# or C++, a function returns a value directly:

// Native C# functionbool IsPositive(int num) {    return num > 0;}

uCalc's callback mechanism acts as a bridge between the uCalc engine and your native code. The ReturnBool method is the tool you use to send a value across that bridge. It is not a direct language return but a command to the uCalc engine, telling it what the result of the callback's execution was.

This design allows for deep integration, enabling you to expose complex, high-performance native logic to the uCalc scripting environment in a controlled and type-aware manner.

Examples

Return and other type-specific versions of Return

ID: 85

See: ArgBool, ArgInt16, ArgInt32, ArgInt64, ReturnBool, ReturnInt16, ReturnInt32, ReturnInt64 
				
					using uCalcSoftware;

var uc = new uCalc();

static void BooleanAnd(uCalc.Callback cb) {
   cb.ReturnBool(cb.ArgBool(1) && cb.ArgBool(2));
}
static void AddInt16(uCalc.Callback cb) {
   //C# promots Int16 to int for arithmetic hence (Int16) to convert it back
   cb.ReturnInt16((Int16)(cb.ArgInt16(1) + cb.ArgInt16(2)));

}
static void AddInt32(uCalc.Callback cb) {
   cb.ReturnInt32(cb.ArgInt32(1) + cb.ArgInt32(2));
}
static void AddInt64(uCalc.Callback cb) {
   cb.ReturnInt64(cb.ArgInt64(1) + cb.ArgInt64(2));
}


uc.DefineFunction("BooleanAnd(x As Bool, y As Bool) As Bool", BooleanAnd);
uc.DefineFunction("AddInt16(x As Int16, y As Int16) As Int16", AddInt16);
uc.DefineFunction("AddInt32(x As Int32, y As Int32) As Int32", AddInt32);
uc.DefineFunction("AddInt64(x As Int64, y As Int64) As Int64", AddInt64);

Console.WriteLine(uc.EvalStr("BooleanAnd(true, false)"));
Console.WriteLine(uc.EvalStr("AddInt16(5.2, 4.1)"));
Console.WriteLine(uc.EvalStr("AddInt32(2, 3)"));
Console.WriteLine(uc.EvalStr("AddInt64(10, 20)"));
				
			
false
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					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

void ucalc_call BooleanAnd(uCalcBase::Callback cb) {
   cb.ReturnBool(cb.ArgBool(1) && cb.ArgBool(2));
}
void ucalc_call AddInt16(uCalcBase::Callback cb) {
   
   cb.ReturnInt16(cb.ArgInt16(1) + cb.ArgInt16(2));
}
void ucalc_call AddInt32(uCalcBase::Callback cb) {
   cb.ReturnInt32(cb.ArgInt32(1) + cb.ArgInt32(2));
}
void ucalc_call AddInt64(uCalcBase::Callback cb) {
   cb.ReturnInt64(cb.ArgInt64(1) + cb.ArgInt64(2));
}
int main() {
   uCalc uc;

   uc.DefineFunction("BooleanAnd(x As Bool, y As Bool) As Bool", BooleanAnd);
   uc.DefineFunction("AddInt16(x As Int16, y As Int16) As Int16", AddInt16);
   uc.DefineFunction("AddInt32(x As Int32, y As Int32) As Int32", AddInt32);
   uc.DefineFunction("AddInt64(x As Int64, y As Int64) As Int64", AddInt64);

   cout << uc.EvalStr("BooleanAnd(true, false)") << endl;
   cout << uc.EvalStr("AddInt16(5.2, 4.1)") << endl;
   cout << uc.EvalStr("AddInt32(2, 3)") << endl;
   cout << uc.EvalStr("AddInt64(10, 20)") << endl;
}
				
			
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					Imports System
Imports uCalcSoftware
Public Module Program
   
   Public Sub BooleanAnd(ByVal cb As uCalc.Callback)
      cb.ReturnBool(cb.ArgBool(1) And cb.ArgBool(2))
   End Sub
   Public Sub AddInt16(ByVal cb As uCalc.Callback)
      
      cb.ReturnInt16(cb.ArgInt16(1) + cb.ArgInt16(2))
   End Sub
   Public Sub AddInt32(ByVal cb As uCalc.Callback)
      cb.ReturnInt32(cb.ArgInt32(1) + cb.ArgInt32(2))
   End Sub
   Public Sub AddInt64(ByVal cb As uCalc.Callback)
      cb.ReturnInt64(cb.ArgInt64(1) + cb.ArgInt64(2))
   End Sub
   Public Sub Main()
      Dim uc As New uCalc()
      
      uc.DefineFunction("BooleanAnd(x As Bool, y As Bool) As Bool", AddressOf BooleanAnd)
      uc.DefineFunction("AddInt16(x As Int16, y As Int16) As Int16", AddressOf AddInt16)
      uc.DefineFunction("AddInt32(x As Int32, y As Int32) As Int32", AddressOf AddInt32)
      uc.DefineFunction("AddInt64(x As Int64, y As Int64) As Int64", AddressOf AddInt64)
      
      Console.WriteLine(uc.EvalStr("BooleanAnd(true, false)"))
      Console.WriteLine(uc.EvalStr("AddInt16(5.2, 4.1)"))
      Console.WriteLine(uc.EvalStr("AddInt32(2, 3)"))
      Console.WriteLine(uc.EvalStr("AddInt64(10, 20)"))
   End Sub
End Module
				
			
false
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