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.

ArgAddr

Method

Product: 

Fast Math Parser

Class: 

Callback

Retrieves a direct memory pointer to the value of an argument passed to a callback function.

Syntax

ArgAddr(int)

Parameters

index
int
The 1-based index of the argument. The first argument is at index 1, the second at 2, and so on.

Return

IntPtr

Returns a raw memory pointer (void* or IntPtr) to the argument's value. This pointer must be cast to the correct type before use.

Remarks

The ArgAddr method is a low-level tool for advanced callback scenarios, providing direct memory access to an argument's value. It is typically used when a strongly-typed accessor (like ArgInt32 or ArgStr) is not available for a specific data type, or when you need to interact with the argument's underlying memory.

Core Use Cases

  1. Generic Value Retrieval: When working with custom or non-standard data types, ArgAddr provides a universal way to get a pointer to the value. You can then use the argument's DataType object to safely read or convert this value.

  2. Modifying ByRef Arguments: If a function parameter is defined with the ByRef modifier, ArgAddr gives you the memory address of the original variable. This allows the callback to modify the variable's value in the caller's scope, a key feature for creating functions with side effects.

ArgAddr vs. ArgPtr

It is crucial to understand the distinction between these two methods:

  • ArgAddr(n): Returns the memory address of the nth argument itself. This is the location on the call stack or in a register where the argument's value is stored.
  • ArgPtr(n): Returns the value of the nth argument, assuming that value is a pointer. It reads the data from the argument's location and interprets it as a memory address.

See the internal test example for a practical demonstration of this difference.

⚖️ Comparative Analysis

In native C/C++, accessing function arguments might involve variadic argument lists (va_list) or direct stack manipulation, which can be unsafe and complex. uCalc's Callback model abstracts this away.

  • Without uCalc: You would rely on the language's native argument passing mechanisms. Interacting with different data types would require templates (C++) or boxing/unboxing (C#), and getting a pointer to an argument can be tricky.
  • With uCalc: ArgAddr provides a consistent, safe, and platform-agnostic way to get a memory pointer to an argument within the sandboxed uCalc environment. It simplifies interoperability between the uCalc engine and the host application's data.

Note: The argument index is 1-based. The first argument is at index 1, not 0.

Examples

How to handle and retrieve various data types (including pointers) within a callback.
				
					using uCalcSoftware;

var uc = new uCalc();

static void MyFunction(uCalc.Callback cb) {
   var uc = cb.uCalc;
   Console.WriteLine("------ MyFunc ------");

   // Retrieve standard 32-bit and 64-bit integer arguments directly
   Console.WriteLine(cb.ArgInt32(1));
   Console.WriteLine(cb.ArgInt64(2));

   // Retrieve the value of a pointer argument by referencing its exact data type.
   Console.WriteLine(uc.ItemOf("Int8").DataType.ToString(cb.ArgAddr(3)));

   // The Item object correctly identifies the type before conversion
   Console.WriteLine(uc.ItemOf("Int").DataType.ToString(cb.ArgPtr(4)));
}

static void MyFunction2(uCalc.Callback cb) {
   var uc = cb.uCalc;
   Console.WriteLine("------ MyFunc2 ------");
   Console.WriteLine(uc.DataTypeOf(BuiltInType.Integer_8).ToString(cb.ArgPtr(1)));
}

static void MyFunction3(uCalc.Callback cb) {
   var uc = cb.uCalc;
   Console.WriteLine("------ MyFunc3 ------");
   Console.WriteLine(uc.DataTypeOf(BuiltInType.Integer_16).ToString(cb.ArgPtr(1)));
}

uc.DefineVariable("x As Int = 123"); // Int32
uc.DefineVariable("xPtr As Int Ptr = AddressOf(x)");
uc.DefineFunction("MyFunc(a As Int32, b As Int64, c As Byte, d As Int Ptr)", MyFunction);
uc.Eval("MyFunc(x*10, 1+1, 255, xPtr)");

uc.DefineVariable("x2 As Int8 = -123");
uc.DefineVariable("xPtr2 As Int8 Ptr = AddressOf(x2)");
uc.DefineFunction("MyFunc2(d As Int8 Ptr)", MyFunction2);
uc.Eval("MyFunc2(xPtr2)");

uc.DefineVariable("x3 As Int16 = 1234");
uc.DefineVariable("xPtr3 As Int16 Ptr = AddressOf(x3)");
uc.DefineFunction("MyFunc3(d As Int16 Ptr)", MyFunction3);
uc.Eval("MyFunc3(xPtr3)");
				
			
------ MyFunc ------
1230
2
-1
123
------ MyFunc2 ------
-123
------ MyFunc3 ------
1234
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

void ucalc_call MyFunction(uCalcBase::Callback cb) {
   auto uc = cb.uCalc();
   cout << "------ MyFunc ------" << endl;

   // Retrieve standard 32-bit and 64-bit integer arguments directly
   cout << cb.ArgInt32(1) << endl;
   cout << cb.ArgInt64(2) << endl;

   // Retrieve the value of a pointer argument by referencing its exact data type.
   cout << uc.ItemOf("Int8").DataType().ToString(cb.ArgAddr(3)) << endl;

   // The Item object correctly identifies the type before conversion
   cout << uc.ItemOf("Int").DataType().ToString(cb.ArgPtr(4)) << endl;
}

void ucalc_call MyFunction2(uCalcBase::Callback cb) {
   auto uc = cb.uCalc();
   cout << "------ MyFunc2 ------" << endl;
   cout << uc.DataTypeOf(BuiltInType::Integer_8).ToString(cb.ArgPtr(1)) << endl;
}

void ucalc_call MyFunction3(uCalcBase::Callback cb) {
   auto uc = cb.uCalc();
   cout << "------ MyFunc3 ------" << endl;
   cout << uc.DataTypeOf(BuiltInType::Integer_16).ToString(cb.ArgPtr(1)) << endl;
}
int main() {
   uCalc uc;
   uc.DefineVariable("x As Int = 123"); // Int32
   uc.DefineVariable("xPtr As Int Ptr = AddressOf(x)");
   uc.DefineFunction("MyFunc(a As Int32, b As Int64, c As Byte, d As Int Ptr)", MyFunction);
   uc.Eval("MyFunc(x*10, 1+1, 255, xPtr)");

   uc.DefineVariable("x2 As Int8 = -123");
   uc.DefineVariable("xPtr2 As Int8 Ptr = AddressOf(x2)");
   uc.DefineFunction("MyFunc2(d As Int8 Ptr)", MyFunction2);
   uc.Eval("MyFunc2(xPtr2)");

   uc.DefineVariable("x3 As Int16 = 1234");
   uc.DefineVariable("xPtr3 As Int16 Ptr = AddressOf(x3)");
   uc.DefineFunction("MyFunc3(d As Int16 Ptr)", MyFunction3);
   uc.Eval("MyFunc3(xPtr3)");
}
				
			
------ MyFunc ------
1230
2
-1
123
------ MyFunc2 ------
-123
------ MyFunc3 ------
1234
				
					Imports System
Imports uCalcSoftware
Public Module Program
   
   Public Sub MyFunction(ByVal cb As uCalc.Callback)
      Dim uc = cb.uCalc
      Console.WriteLine("------ MyFunc ------")
      
      '// Retrieve standard 32-bit and 64-bit integer arguments directly
      Console.WriteLine(cb.ArgInt32(1))
      Console.WriteLine(cb.ArgInt64(2))
      
      '// Retrieve the value of a pointer argument by referencing its exact data type.
      Console.WriteLine(uc.ItemOf("Int8").DataType.ToString(cb.ArgAddr(3)))
      
      '// The Item object correctly identifies the type before conversion
      Console.WriteLine(uc.ItemOf("Int").DataType.ToString(cb.ArgPtr(4)))
   End Sub
   
   Public Sub MyFunction2(ByVal cb As uCalc.Callback)
      Dim uc = cb.uCalc
      Console.WriteLine("------ MyFunc2 ------")
      Console.WriteLine(uc.DataTypeOf(BuiltInType.Integer_8).ToString(cb.ArgPtr(1)))
   End Sub
   
   Public Sub MyFunction3(ByVal cb As uCalc.Callback)
      Dim uc = cb.uCalc
      Console.WriteLine("------ MyFunc3 ------")
      Console.WriteLine(uc.DataTypeOf(BuiltInType.Integer_16).ToString(cb.ArgPtr(1)))
   End Sub
   Public Sub Main()
      Dim uc As New uCalc()
      uc.DefineVariable("x As Int = 123") '// Int32
      uc.DefineVariable("xPtr As Int Ptr = AddressOf(x)")
      uc.DefineFunction("MyFunc(a As Int32, b As Int64, c As Byte, d As Int Ptr)", AddressOf MyFunction)
      uc.Eval("MyFunc(x*10, 1+1, 255, xPtr)")
      
      uc.DefineVariable("x2 As Int8 = -123")
      uc.DefineVariable("xPtr2 As Int8 Ptr = AddressOf(x2)")
      uc.DefineFunction("MyFunc2(d As Int8 Ptr)", AddressOf MyFunction2)
      uc.Eval("MyFunc2(xPtr2)")
      
      uc.DefineVariable("x3 As Int16 = 1234")
      uc.DefineVariable("xPtr3 As Int16 Ptr = AddressOf(x3)")
      uc.DefineFunction("MyFunc3(d As Int16 Ptr)", AddressOf MyFunction3)
      uc.Eval("MyFunc3(xPtr3)")
   End Sub
End Module
				
			
------ MyFunc ------
1230
2
-1
123
------ MyFunc2 ------
-123
------ MyFunc3 ------
1234
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