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.

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

ID: 93

See: EvaluateBool, ValueStr(bool) 
				
					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
Explore 600+ other examples
				
					#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
Explore 600+ other examples
				
					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
Explore 600+ other examples