EvalMenu

Applies to:Fast Math Parser
Evaluating an expression
Remarks
If you pass a math expression to Eval, it will evaluate it just like a scientific calculator would and return a result: #c Answer = uc.Eval("5+4*10") #c uCalc also handles string expressions. #c AnswerStr = uc.EvalStr("'Hello ' + 'world!'") #c For a full list of core functions and operators, See Core Functions and Operators
Example 1: Evaluating expressions 

Console.WriteLine(uc.Eval("1+1")) ' Returns 2
Console.WriteLine(uc.Eval("5*(3+9)^2")) ' Returns 720     
Console.WriteLine(uc.Eval("Length('This is a test')")) ' Returns 14

          

Console.WriteLine(uc.Eval("1+1")); // Returns 2;
Console.WriteLine(uc.Eval("5*(3+9)^2")); // Returns 720;     
Console.WriteLine(uc.Eval("Length('This is a test')")); // Returns 14;

          

      WriteLn(uc.Eval('1+1')); // Returns 2;
      WriteLn(uc.Eval('5*(3+9)^2')); // Returns 720;     
      WriteLn(uc.Eval('Length("This is a test")')); // Returns 14;

          

cout << uc.Eval("1+1") << endl; // Returns 2;
cout << uc.Eval("5*(3+9)^2") << endl; // Returns 720;     
cout << uc.Eval("Length('This is a test')") << endl; // Returns 14;

          

Console::WriteLine(uc.Eval("1+1")); // Returns 2;
Console::WriteLine(uc.Eval("5*(3+9)^2")); // Returns 720;     
Console::WriteLine(uc.Eval("Length('This is a test')")); // Returns 14;
Example 2: Performing a summation; a return value is needed only at the very end 

Dim VariableX = uc.DefineVariable("x")
Dim Total = uc.DefineVariable("Total")
Dim Expression As string
Console.Write("Enter an expression (Ex: Total = Total + x^2 + 5): ")
Expression = Console.ReadLine()
Dim ParsedExpr = uc.Parse(Expression)

Dim x As double
for x = 1 To 10
   VariableX.SetVariableValue(x)
   ParsedExpr.Execute()
   Console.WriteLine(uc.Eval("x") + "   Sub total = " + uc.Eval("Total"))
Next
' Output
' 1   Sub total = 6
' 2   Sub total = 15
' 3   Sub total = 29
' 4   Sub total = 50
' 5   Sub total = 80
' 6   Sub total = 121
' 7   Sub total = 175
' 8   Sub total = 244
' 9   Sub total = 330
' 10   Sub total = 435

          

var VariableX = uc.DefineVariable("x");
var Total = uc.DefineVariable("Total");
string Expression;
Console.Write("Enter an expression (Ex: Total = Total + x^2 + 5): ");
Expression = Console.ReadLine();
var ParsedExpr = uc.Parse(Expression);

for (double x = 1; x <= 10; x = x + 1) {
   VariableX.SetVariableValue(x);
   ParsedExpr.Execute();
   Console.WriteLine(uc.Eval("x") + "   Sub total = " + uc.Eval("Total"));
}
// Output
// 1   Sub total = 6
// 2   Sub total = 15
// 3   Sub total = 29
// 4   Sub total = 50
// 5   Sub total = 80
// 6   Sub total = 121
// 7   Sub total = 175
// 8   Sub total = 244
// 9   Sub total = 330
// 10   Sub total = 435

Console.WriteLine("Total = " + uc.Eval("Total")); // Returns "Total = 435";

ParsedExpr.Release();
VariableX.Release();

          

//var VariableX = uc.DefineVariable('x');
//var Total = uc.DefineVariable('Total');
      Write('Enter an expression (Ex: Total = Total + x^2 + 5): ')
Expression = ReadLn();
//var ParsedExpr = uc.Parse(Expression);

      for x := 1 to 10 do
begin
   VariableX.SetVariableValue(x);
         ParsedExpr.Execute();
         WriteLn(uc.Eval('x') + '   Sub total = ' + uc.Eval('Total'));
End;
      // Output
// 1   Sub total = 6
// 2   Sub total = 15
// 3   Sub total = 29
// 4   Sub total = 50
// 5   Sub total = 80
// 6   Sub total = 121
// 7   Sub total = 175
// 8   Sub total = 244
// 9   Sub total = 330
// 10   Sub total = 435

          

auto VariableX = uc.DefineVariable("x");
auto Total = uc.DefineVariable("Total");
string Expression;      
cout << "Enter an expression (Ex: Total = Total + x^2 + 5): " << endl;
cin >> Expression; // Ex: Total = Total + x^2 + 5
auto ParsedExpr = uc.Parse(Expression);

for (double x = 1; x <= 10; x = x + 1) {
   VariableX.SetVariableValue(x);
   ParsedExpr.Execute();
   cout << uc.Eval("x") << "   Sub total = " << uc.Eval("Total") << endl;
}
// Output
// 1   Sub total = 6
// 2   Sub total = 15
// 3   Sub total = 29
// 4   Sub total = 50
// 5   Sub total = 80
// 6   Sub total = 121
// 7   Sub total = 175
// 8   Sub total = 244
// 9   Sub total = 330
// 10   Sub total = 435

cout << "Total = " << uc.Eval("Total") << endl; // Returns "Total = 435";

ParsedExpr.Release();
VariableX.Release();

          

auto VariableX = uc.DefineVariable("x");
auto Total = uc.DefineVariable("Total");
string ^ Expression;
Console::Write("Enter an expression (Ex: Total = Total + x^2 + 5): ");
Expression = Console::ReadLine();
auto ParsedExpr = uc.Parse(Expression);

for (double x = 1; x <= 10; x = x + 1) {
   VariableX.SetVariableValue(x);
   ParsedExpr.Execute();
   Console::WriteLine(uc.Eval("x") + "   Sub total = " + uc.Eval("Total"));
}
// Output
// 1   Sub total = 6
// 2   Sub total = 15
// 3   Sub total = 29
// 4   Sub total = 50
// 5   Sub total = 80
// 6   Sub total = 121
// 7   Sub total = 175
// 8   Sub total = 244
// 9   Sub total = 330
// 10   Sub total = 435

Console::WriteLine("Total = " + uc.Eval("Total")); // Returns "Total = 435";

ParsedExpr.Release();
VariableX.Release();
Example 3: Defining various items 

uc.Define("Function: f(x, y) = x + y")
uc.Define("Operator: {a As String} CONCAT {b As String} As String = a + b")
uc.Define("Variable: MyVar = 123")
uc.Define("Lock ~~ Variable: Pi = 3.14"): ' like uc.DefineConstant
uc.Define("Syntax: aa ::= bb")
      
Console.WriteLine(uc.Eval("f(10, 20) + MyVar")) ' Returns 153
Console.WriteLine(uc.Eval("Pi")) ' Returns 3.14
Console.WriteLine(uc.EvalStr("'Hello ' CONCAT 'World!'")) ' Returns "Hello World!"
Console.WriteLine(uc.Expand("aa, bb, cc")) ' Returns "bb, bb, cc"

          

uc.Define("Function: f(x, y) = x + y");
uc.Define("Operator: {a As String} CONCAT {b As String} As String = a + b");
uc.Define("Variable: MyVar = 123");
uc.Define("Lock ~~ Variable: Pi = 3.14"); // like uc.DefineConstant
uc.Define("Syntax: aa ::= bb");

Console.WriteLine(uc.Eval("f(10, 20) + MyVar")); // Returns 153;
Console.WriteLine(uc.Eval("Pi")); // Returns 3.14;
Console.WriteLine(uc.EvalStr("'Hello ' CONCAT 'World!'")); // Returns "Hello World!";
Console.WriteLine(uc.Expand("aa, bb, cc")); // Returns "bb, bb, cc";

uc.GetItemOf("Pi").Release();

          

      uc.Define('Function: f(x, y) = x + y');
      uc.Define('Operator: {a As String} CONCAT {b As String} As String = a + b');
      uc.Define('Variable: MyVar = 123');
      uc.Define('Lock ~~ Variable: Pi = 3.14'); // like uc.DefineConstant
      uc.Define('Syntax: aa ::= bb');
      
      WriteLn(uc.Eval('f(10, 20) + MyVar')); // Returns 153;
      WriteLn(uc.Eval('Pi')); // Returns 3.14;
      WriteLn(uc.EvalStr('"Hello " CONCAT "World!"')); // Returns 'Hello World!';
      WriteLn(uc.Expand('aa, bb, cc')); // Returns 'bb, bb, cc';

          

uc.Define("Function: f(x, y) = x + y");
uc.Define("Operator: {a As String} CONCAT {b As String} As String = a + b");
uc.Define("Variable: MyVar = 123");
uc.Define("Lock ~~ Variable: Pi = 3.14"); // like uc.DefineConstant
uc.Define("Syntax: aa ::= bb");

cout << uc.Eval("f(10, 20) + MyVar") << endl; // Returns 153;
cout << uc.Eval("Pi") << endl; // Returns 3.14;
cout << uc.EvalStr("'Hello ' CONCAT 'World!'") << endl; // Returns "Hello World!";
cout << uc.Expand("aa, bb, cc") << endl; // Returns "bb, bb, cc";

uc.GetItemOf("Pi").Release();

          

uc.Define("Function: f(x, y) = x + y");
uc.Define("Operator: {a As String} CONCAT {b As String} As String = a + b");
uc.Define("Variable: MyVar = 123");
uc.Define("Lock ~~ Variable: Pi = 3.14"); // like uc.DefineConstant
uc.Define("Syntax: aa ::= bb");

Console::WriteLine(uc.Eval("f(10, 20) + MyVar")); // Returns 153;
Console::WriteLine(uc.Eval("Pi")); // Returns 3.14;
Console::WriteLine(uc.EvalStr("'Hello ' CONCAT 'World!'")); // Returns "Hello World!";
Console::WriteLine(uc.Expand("aa, bb, cc")); // Returns "bb, bb, cc";

uc.GetItemOf("Pi").Release();
Example 4: Setting variables of any data type 

Dim Int32Var = uc.DefineVariable("Int32Var As Int32")
Dim ByteVar = uc.DefineVariable("ByteVar As Byte")
Dim StrVar = uc.DefineVariable("StrVar As String")
Dim SngVar = uc.DefineVariable("SngVar As Single")

Int32Var.SetVariableValueAny("4.25"): ' Will be converted to integer
ByteVar.SetVariableValueAny("-1"): ' Will be converted to unsigned byte
StrVar.SetVariableValueAny("'Test'")
SngVar.SetVariableValueAny("1.25")

Console.WriteLine(uc.Eval("Int32Var")) ' Returns 4
Console.WriteLine(uc.Eval("ByteVar")) ' Returns 255
Console.WriteLine(uc.EvalStr("StrVar")) ' Returns "Test"
Console.WriteLine(uc.EvalStr("SngVar")) ' Returns 1.25

          

var Int32Var = uc.DefineVariable("Int32Var As Int32");
var ByteVar = uc.DefineVariable("ByteVar As Byte");
var StrVar = uc.DefineVariable("StrVar As String");
var SngVar = uc.DefineVariable("SngVar As Single");

Int32Var.SetVariableValueAny("4.25"); // Will be converted to integer
ByteVar.SetVariableValueAny("-1");    // Will be converted to unsigned byte
StrVar.SetVariableValueAny("'Test'");
SngVar.SetVariableValueAny("1.25");

Console.WriteLine(uc.Eval("Int32Var")); // Returns 4;
Console.WriteLine(uc.Eval("ByteVar")); // Returns 255;
Console.WriteLine(uc.EvalStr("StrVar")); // Returns "Test";
Console.WriteLine(uc.EvalStr("SngVar")); // Returns 1.25;

          

//var Int32Var = uc.DefineVariable('Int32Var As Int32');
//var ByteVar = uc.DefineVariable('ByteVar As Byte');
//var StrVar = uc.DefineVariable('StrVar As String');
//var SngVar = uc.DefineVariable('SngVar As Single');

      Int32Var.SetVariableValueAny('4.25'); // Will be converted to integer
      ByteVar.SetVariableValueAny('-1');    // Will be converted to unsigned byte
      StrVar.SetVariableValueAny('"Test"');
      SngVar.SetVariableValueAny('1.25');

      WriteLn(uc.Eval('Int32Var')); // Returns 4;
      WriteLn(uc.Eval('ByteVar')); // Returns 255;
      WriteLn(uc.EvalStr('StrVar')); // Returns 'Test';
      WriteLn(uc.EvalStr('SngVar')); // Returns 1.25;

          

auto Int32Var = uc.DefineVariable("Int32Var As Int32");
auto ByteVar = uc.DefineVariable("ByteVar As Byte");
auto StrVar = uc.DefineVariable("StrVar As String");
auto SngVar = uc.DefineVariable("SngVar As Single");

Int32Var.SetVariableValueAny("4.25"); // Will be converted to integer
ByteVar.SetVariableValueAny("-1");    // Will be converted to unsigned byte
StrVar.SetVariableValueAny("'Test'");
SngVar.SetVariableValueAny("1.25");

cout << uc.Eval("Int32Var") << endl; // Returns 4;
cout << uc.Eval("ByteVar") << endl; // Returns 255;
cout << uc.EvalStr("StrVar") << endl; // Returns "Test";
cout << uc.EvalStr("SngVar") << endl; // Returns 1.25;

          

auto Int32Var = uc.DefineVariable("Int32Var As Int32");
auto ByteVar = uc.DefineVariable("ByteVar As Byte");
auto StrVar = uc.DefineVariable("StrVar As String");
auto SngVar = uc.DefineVariable("SngVar As Single");

Int32Var.SetVariableValueAny("4.25"); // Will be converted to integer
ByteVar.SetVariableValueAny("-1");    // Will be converted to unsigned byte
StrVar.SetVariableValueAny("'Test'");
SngVar.SetVariableValueAny("1.25");

Console::WriteLine(uc.Eval("Int32Var")); // Returns 4;
Console::WriteLine(uc.Eval("ByteVar")); // Returns 255;
Console::WriteLine(uc.EvalStr("StrVar")); // Returns "Test";
Console::WriteLine(uc.EvalStr("SngVar")); // Returns 1.25;
DLL import code
<DllImport(uCalcDLL, CharSet:=CharSet.Ansi, CallingConvention:=CallingConvention.Cdecl, EntryPoint:="Eval")> _

Private Function Eval__(ByVal uCalcHandle As IntPtr,ByVal Expression As String) As  Double
End Function
            
[DllImport(uCalcDLL, CharSet=CharSet.Ansi, CallingConvention=CallingConvention.Cdecl, EntryPoint="Eval")]

protected static extern  double Eval_(IntPtr uCalcHandle, string Expression);
            
{DLLImport}function Eval__(uCalcHandle: System.Pointer;Expression: AnsiString):  Double; cdecl; external uCalcDLL name 'Eval';

            
typedef  double (* __Eval)(void *uCalcHandle, CONSTCHAR Expression ); 

            
[DllImport(uCalcLib, CharSet=CharSet::Ansi, CallingConvention=CallingConvention::Cdecl, EntryPoint = "Eval")]

static double Eval_(void *  uCalcHandle, MARSHALSTR Expression);
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