使用 ICustomFunction 功能

介绍

本文介绍了如何使用 ICustomFunction 功能通过 Aspose.Cells API 实现自定义函数。

ICustomFunction 接口允许您添加自定义公式计算函数以扩展 Aspose.Cells 核心计算引擎以满足某些需求。此功能对于在模板文件或代码中定义自定义（用户定义）函数很有用，在该代码中自定义函数可以像任何其他默认 Microsoft Excel 函数一样使用 Aspose.Cells API 实现和评估。

使用 ICustomFunction 功能

以下示例代码实现了 ICustomFunction 接口，该接口计算并返回两个自定义函数的值，即 MySampleFunc() 和 YourSampleFunc()。这些自定义函数分别位于单元格 A1 和 A2 中。然后它调用 IWorkbook.CalculateFormula(false, ICustomFunction) 方法来调用 ICustomFunction.CalculateCustomFunction() 方法的实现。然后，它在控制台上打印 A1 和 A2 的值，这些值实际上是 ICustomFunction.CalculateCustomFunction() 返回的值。请参阅下面示例代码的控制台输出以获得更多帮助。

示例代码

//For complete examples and data files, please go to https://github.com/aspose-cells/Aspose.Cells-for-C

//Implement ICustomFunction interface
class CustomFunction : public ICustomFunction
{
public:
	//Evalaute and return the values of your custom functions
	intrusive_ptr<Aspose::Cells::System::Object>
		CalculateCustomFunction(
			intrusive_ptr<Aspose::Cells::System::String> functionName,
			intrusive_ptr<Aspose::Cells::System::Collections::ArrayList> paramsList,
			intrusive_ptr<Aspose::Cells::System::Collections::ArrayList> contextObjects)
	{
		if (functionName->Equals(new String("MySampleFunc")))
		{
			return new String("MY sample function was called successfully.");
		}

		if (functionName->Equals(new String("YourSampleFunc")))
		{
			return new String("YOUR sample function was called successfully.");
		}

		return NULL;
	}

};

//Using ICustomFunction Feature
void  UsingICustomFunctionFeature()
{
	//Create workbook
	intrusive_ptr<IWorkbook> wb = Factory::CreateIWorkbook();

	//Access first worksheet in the workbook
	intrusive_ptr<IWorksheet> ws = wb->GetIWorksheets()->GetObjectByIndex(0);

	//Adding custom formulas to Cell A1 and A2
	ws->GetICells()->GetObjectByIndex(new String("A1"))->SetFormula(new String("=MySampleFunc()"));
	ws->GetICells()->GetObjectByIndex(new String("A2"))->SetFormula(new String("=YourSampleFunc()"));

	// Calcualting Formulas
	intrusive_ptr<CustomFunction> custFunc = new CustomFunction();
	wb->CalculateFormula(false, custFunc);

	//Print the value of cell A1 and A2 after the calculation of custom function implemented by us.
	intrusive_ptr<String> valA1 = ws->GetICells()->GetObjectByIndex(new String("A1"))->GetStringValue();
	intrusive_ptr<String> valA2 = ws->GetICells()->GetObjectByIndex(new String("A2"))->GetStringValue();

	//Print the values on console
	StringPtr str1 = new String("Value of A1: ");
	Console::WriteLine(str1->StringAppend(valA1));
	StringPtr str2 = new String("Value of A2: ");
	Console::WriteLine(str2->StringAppend(valA2));
}

控制台输出

 Value of A1: MY sample function was called successfully.

Value of A2: YOUR sample function was called successfully.