uCalc API Version: 2.1.3-preview.2 Released: 6/16/2026

Warning

uCalc API Preview Release Notice:The documentation describes the intended behavior of the API. The current preview build contains incomplete features, unoptimized performance, and is subject to breaking changes.

EvaluateBool

Method

Product: 

Fast Math Parser

Class: 

Expression

Evaluates a pre-parsed boolean expression, returning the native true or false result efficiently.

Syntax

EvaluateBool()

Parameters

[None]

Return

bool

The result of the evaluated Boolean expression

Remarks

The EvaluateBool method is the high-performance counterpart to Evaluate for expressions that result in a boolean value. It executes a pre-compiled expression object, created by Parse, and returns the native true or false result.

This method is ideal for performance-critical scenarios, such as evaluating conditions inside a loop, where the overhead of parsing the same string repeatedly would be prohibitive.

⚙️ How It Works

Expressions involving comparison operators (<, >, ==, <>), logical operators (And, Or, Not), or functions that return a boolean will produce a boolean result. When you Parse such an expression, uCalc creates a compiled object typed to return a boolean. EvaluateBool is the most direct and efficient way to execute this object.

EvaluateBool vs. Evaluate

While the generic Evaluate method can also return a boolean result (which it casts to a double where 1.0 is true and 0.0 is false), EvaluateBool has distinct advantages:

FeatureEvaluateBool()Evaluate()EvaluateStr()
Return TypeNative booldoublestring
Type Safety🟢 High. Fails predictably if expression is not boolean.🟡 Medium. Casts boolean to number.🟢 High. Converts boolean to text.
Performance🟢 Highest for boolean logic.🟡 High, but with a slight overhead for type casting.🔴 Lowest due to string allocation/formatting.
Use CaseConditional logic, loops, validation rules.General numeric calculations.User-facing display, logging.

💡 Comparative Analysis

In native languages, you might use compiled lambda expressions or function pointers for dynamic conditional logic.

  • C# Func<bool>: A Func<bool> delegate can be compiled from an expression tree for performance, but building that tree from a raw string is a complex, multi-step process.
  • Standard C++: Evaluating string-based boolean logic typically requires integrating a full-blown parsing library.

uCalc provides a much simpler workflow: Parse a string once, then call EvaluateBool in a tight loop. This delivers the performance of a compiled delegate with the flexibility of dynamic string input, offering a powerful middle ground between static code and heavy scripting engines.

Examples

EvaluateBool, also ValueStr which converts numeric value to string
				
					using uCalcSoftware;

var uc = new uCalc();

var VariableX = uc.DefineVariable("x");
var ParsedExpr = uc.Parse("x > 3"); // The > operation returns a Boolean instead of the default floating point

for (double x = 1; x <= 5; x++) {
   VariableX.Value(x);
   Console.WriteLine($"x = {VariableX.ValueStr()}  x > 3 is {ParsedExpr.EvaluateBool()}");
}

ParsedExpr.Release();
VariableX.Release();
				
			
x = 1  x > 3 is False
x = 2  x > 3 is False
x = 3  x > 3 is False
x = 4  x > 3 is True
x = 5  x > 3 is True
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

#define tf(IsTrue) ((IsTrue) ? "True" : "False")

int main() {
   uCalc uc;

   auto VariableX = uc.DefineVariable("x");
   auto ParsedExpr = uc.Parse("x > 3"); // The > operation returns a Boolean instead of the default floating point

   for (double x = 1; x <= 5; x++) {
      VariableX.Value(x);
      cout << "x = " << VariableX.ValueStr() << "  x > 3 is " << tf(ParsedExpr.EvaluateBool()) << endl;
   }

   ParsedExpr.Release();
   VariableX.Release();
}
				
			
x = 1  x > 3 is False
x = 2  x > 3 is False
x = 3  x > 3 is False
x = 4  x > 3 is True
x = 5  x > 3 is True
				
					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      
      Dim VariableX = uc.DefineVariable("x")
      Dim ParsedExpr = uc.Parse("x > 3") '// The > operation returns a Boolean instead of the default floating point
      
      For x  As Double = 1 To 5
         VariableX.Value(x)
         Console.WriteLine($"x = {VariableX.ValueStr()}  x > 3 is {ParsedExpr.EvaluateBool()}")
      Next
      
      ParsedExpr.Release()
      VariableX.Release()
   End Sub
End Module
				
			
x = 1  x > 3 is False
x = 2  x > 3 is False
x = 3  x > 3 is False
x = 4  x > 3 is True
x = 5  x > 3 is True
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