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.

Parse

Method

Product: 

Fast Math Parser

Class: 

uCalc

Compiles a string expression into an intermediate, reusable object for high-performance evaluation.

Syntax

Parse(string, DataType)

Parameters

expression
string
The string containing the mathematical or logical expression to compile.
returnType
DataType
(Default = Empty)
Optional. The explicit return data type for the expression. If omitted, the type is inferred from the expression's content.

Return

Expression

An Expression object representing the compiled, ready-to-evaluate form of the input string.

Remarks

The Parse method is the first step in uCalc's high-performance, two-stage evaluation model. It takes a string expression and compiles it into a reusable Expression object. This object can then be evaluated repeatedly using methods like Evaluate or EvaluateStr.

🚀 The Performance Advantage: Parse Once, Evaluate Many

The most significant advantage of this two-step process is performance. Parsing an expression—analyzing its syntax and building an execution plan—is computationally more expensive than evaluating it. If you need to calculate the same formula multiple times (e.g., in a loop with changing variable values), using Parse is far more efficient than calling Eval or EvalStr repeatedly.

  • Inefficient (Repeated Parsing): for (i = 1 to 1000) result = uc.Eval("x*2+y");
  • Efficient (Parse Once): var p = uc.Parse("x*2+y"); for (i = 1 to 1000) result = p.Evaluate();

⚙️ Syntax and Features

The expression string passed to Parse can leverage the full power of the uCalc engine:

  • It can contain built-in or user-defined Functions and Operators.
  • It is automatically pre-processed by rules defined in the ExpressionTransformer, allowing you to create custom syntax.
  • The return type of the expression can be explicitly set or automatically inferred. If no type can be deduced, the instance's DefaultDataType (typically Double) is used.

🧠 Memory Management

An Expression object created by Parse holds resources and must be released when no longer needed to prevent memory leaks. You can manage its lifecycle in two ways:

  1. Explicit Release: Manually call the Expression.Release() method.
  2. Scoped Release (Recommended): Use language-specific constructs for automatic resource management.
    • C#: Create the object within a using statement.
    • C++: Create the Expression object on the stack (RAII).
### ⚖️ Comparative Analysis*   **vs. `Eval()` in Scripting Languages (Python, JS)**: While `eval()` combines parsing and evaluation into one step, uCalc's `Parse` exposes the intermediate compiled object. This gives developers granular control, enabling performance optimizations and introspection (e.g., checking an expression's return type before evaluating it).*   **vs. C# Expression Trees**: Building expression trees in C# from strings is complex. `Parse` provides a simple, direct way to achieve a similar result at runtime from dynamic user input.*   **vs. `uCalc.Eval()` and `uCalc.EvalStr()`**: These methods are convenient for single-use evaluations. Use `Parse` when you anticipate evaluating the same expression structure more than once.

Examples

A simple demonstration of parsing an expression and then evaluating it.

ID: 396

See: Parse 
				
					using uCalcSoftware;

var uc = new uCalc();
Console.WriteLine("Parsing the expression '100 / 4'...");
using (var parsedExpr = new uCalc.Expression("100 / 4")) {
   //var parsedExpr = uc.Parse("100 / 4");

   Console.WriteLine("Evaluating the result...");
   Console.WriteLine($"Result: {parsedExpr.Evaluate()}");
}
				
			
Parsing the expression '100 / 4'...
Evaluating the result...
Result: 25
Explore 600+ other examples
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   cout << "Parsing the expression '100 / 4'..." << endl;
   {
      uCalc::Expression parsedExpr("100 / 4");
      parsedExpr.Owned(); // Causes parsedExpr to be released when it goes out of scope
      //var parsedExpr = uc.Parse("100 / 4");

      cout << "Evaluating the result..." << endl;
      cout << "Result: " << parsedExpr.Evaluate() << endl;
   }
}
				
			
Parsing the expression '100 / 4'...
Evaluating the result...
Result: 25
Explore 600+ other examples
				
					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Console.WriteLine("Parsing the expression '100 / 4'...")
      Using parsedExpr As New uCalc.Expression("100 / 4")
         '//var parsedExpr = uc.Parse("100 / 4");
         
         Console.WriteLine("Evaluating the result...")
         Console.WriteLine($"Result: {parsedExpr.Evaluate()}")
      End Using
   End Sub
End Module
				
			
Parsing the expression '100 / 4'...
Evaluating the result...
Result: 25
Explore 600+ other examples
Illustrates the core relationship between the uCalc engine, an Item (variable), and a compiled Expression.

ID: 31

See: Evaluate, Introduction, Memory Management, Parse, Release, Release, The uCalc Object Model - A High-Level Overview, uCalc Fast Math Parser, Value(double) 
				
					using uCalcSoftware;

var uc = new uCalc();
var VariableX = uc.DefineVariable("x");
var Expression = "x^2 * 10"; // Replace this with your expression

Console.WriteLine("--- Efficient: Parse() once, then Evaluate() in a loop ---");
var ParsedExpr = uc.Parse(Expression);
for (double x = 1; x <= 10; x++) {
   VariableX.Value(x);
   Console.WriteLine(ParsedExpr.Evaluate());
}

ParsedExpr.Release();
VariableX.Release();
				
			
--- Efficient: Parse() once, then Evaluate() in a loop ---
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Explore 600+ other examples
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   auto VariableX = uc.DefineVariable("x");
   auto Expression = "x^2 * 10"; // Replace this with your expression

   cout << "--- Efficient: Parse() once, then Evaluate() in a loop ---" << endl;
   auto ParsedExpr = uc.Parse(Expression);
   for (double x = 1; x <= 10; x++) {
      VariableX.Value(x);
      cout << ParsedExpr.Evaluate() << endl;
   }

   ParsedExpr.Release();
   VariableX.Release();
}
				
			
--- Efficient: Parse() once, then Evaluate() in a loop ---
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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 Expression = "x^2 * 10" '// Replace this with your expression
      
      Console.WriteLine("--- Efficient: Parse() once, then Evaluate() in a loop ---")
      Dim ParsedExpr = uc.Parse(Expression)
      For x  As Double = 1 To 10
         VariableX.Value(x)
         Console.WriteLine(ParsedExpr.Evaluate())
      Next
      
      ParsedExpr.Release()
      VariableX.Release()
   End Sub
End Module
				
			
--- Efficient: Parse() once, then Evaluate() in a loop ---
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40
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160
250
360
490
640
810
1000
Explore 600+ other examples
Displaying Integer (Int32) results with Evaluate32

ID: 32

See: EvaluateInt32, Parse, Parse(string, string), ValueStr, ValueStr(bool) 
				
					using uCalcSoftware;

var uc = new uCalc();
var VariableX = uc.DefineVariable("x");

var ParsedExpr = uc.Parse("x / 2", "Integer"); // Causes output of "x / 2" to convert to an integer

// NOTE: EvaluateInt32 should only be used when Parse() explicitly specifies Integer
// (Or Int, or Int32) as the second argument, or if the expression evaluates to an integer
// (such as evaluating a variable that was explicitly defined as integer;
// other arithmetic operators typically evaluate to Double floating point).

for (double x = 1; x <= 10; x++) {
   VariableX.Value(x);
   Console.WriteLine("x = " + VariableX.ValueStr() + "  Result = " + (ParsedExpr.EvaluateInt32()).ToString());
}

ParsedExpr.Release();
VariableX.Release();
				
			
x = 1  Result = 0
x = 2  Result = 1
x = 3  Result = 1
x = 4  Result = 2
x = 5  Result = 2
x = 6  Result = 3
x = 7  Result = 3
x = 8  Result = 4
x = 9  Result = 4
x = 10  Result = 5
Explore 600+ other examples
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   auto VariableX = uc.DefineVariable("x");

   auto ParsedExpr = uc.Parse("x / 2", "Integer"); // Causes output of "x / 2" to convert to an integer

   // NOTE: EvaluateInt32 should only be used when Parse() explicitly specifies Integer
   // (Or Int, or Int32) as the second argument, or if the expression evaluates to an integer
   // (such as evaluating a variable that was explicitly defined as integer;
   // other arithmetic operators typically evaluate to Double floating point).

   for (double x = 1; x <= 10; x++) {
      VariableX.Value(x);
      cout << "x = " + VariableX.ValueStr() + "  Result = " + to_string(ParsedExpr.EvaluateInt32()) << endl;
   }

   ParsedExpr.Release();
   VariableX.Release();
}
				
			
x = 1  Result = 0
x = 2  Result = 1
x = 3  Result = 1
x = 4  Result = 2
x = 5  Result = 2
x = 6  Result = 3
x = 7  Result = 3
x = 8  Result = 4
x = 9  Result = 4
x = 10  Result = 5
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 / 2", "Integer") '// Causes output of "x / 2" to convert to an integer
      
      '// NOTE: EvaluateInt32 should only be used when Parse() explicitly specifies Integer
      '// (Or Int, or Int32) as the second argument, or if the expression evaluates to an integer
      '// (such as evaluating a variable that was explicitly defined as integer;
      '// other arithmetic operators typically evaluate to Double floating point).
      
      For x  As Double = 1 To 10
         VariableX.Value(x)
         Console.WriteLine("x = " + VariableX.ValueStr() + "  Result = " + (ParsedExpr.EvaluateInt32()).ToString())
      Next
      
      ParsedExpr.Release()
      VariableX.Release()
   End Sub
End Module
				
			
x = 1  Result = 0
x = 2  Result = 1
x = 3  Result = 1
x = 4  Result = 2
x = 5  Result = 2
x = 6  Result = 3
x = 7  Result = 3
x = 8  Result = 4
x = 9  Result = 4
x = 10  Result = 5
Explore 600+ other examples
Using the parse-evaluate pattern for high-performance calculations in a loop with a changing variable w/ stopwatch.

ID: 1460

See: DefineVariable, Evaluate, Optimizing Performance in Loops, Parse, Value(double) 
				
					using uCalcSoftware;

var uc = new uCalc();
var variableX = uc.DefineVariable("x");
var userExpression = "x * 2 + 5";
var Total = 0.0;
var UpperBound = 1000000; // One million

// Parse the expression just once before the loop begins.
var parsedExpr = uc.Parse(userExpression);

var stopwatch = System.Diagnostics.Stopwatch.StartNew();
for (double x = 1; x <= UpperBound; x++) {
   variableX.Value(x);
   Total = Total + parsedExpr.Evaluate();
}
stopwatch.Stop();
//Uncomment the following line to reveal the actual speed:
//Console.WriteLine($"Elapsed Milliseconds: {stopwatch.ElapsedMilliseconds} ms");

Console.Write("Sum(1, "); Console.Write(UpperBound); Console.Write(", "); Console.Write(userExpression); Console.Write(") = "); Console.Write(Total);
				
			
Sum(1, 1000000, x * 2 + 5) = 1000006000000
Explore 600+ other examples
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   auto variableX = uc.DefineVariable("x");
   auto userExpression = "x * 2 + 5";
   auto Total = 0.0;
   auto UpperBound = 1000000; // One million

   // Parse the expression just once before the loop begins.
   auto parsedExpr = uc.Parse(userExpression);


   for (double x = 1; x <= UpperBound; x++) {
      variableX.Value(x);
      Total = Total + parsedExpr.Evaluate();
   }

   cout << "Sum(1, " << UpperBound << ", " << userExpression << ") = " << (long long)Total;
}
				
			
Sum(1, 1000000, x * 2 + 5) = 1000006000000
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 userExpression = "x * 2 + 5"
      Dim Total = 0.0
      Dim UpperBound = 1000000 '// One million
      
      '// Parse the expression just once before the loop begins.
      Dim parsedExpr = uc.Parse(userExpression)
      
      Dim stopwatch = System.Diagnostics.Stopwatch.StartNew()
      For x  As Double = 1 To UpperBound
         variableX.Value(x)
         Total = Total + parsedExpr.Evaluate()
      Next
      stopwatch.Stop()
      '//Uncomment the following line to reveal the actual speed:
      '//Console.WriteLine($"Elapsed Milliseconds: {stopwatch.ElapsedMilliseconds} ms");
      
      Console.Write("Sum(1, ")
      Console.Write(UpperBound)
      Console.Write(", ")
      Console.Write(userExpression)
      Console.Write(") = ")
      Console.Write(Total)
   End Sub
End Module
				
			
Sum(1, 1000000, x * 2 + 5) = 1000006000000
Explore 600+ other examples