C语言 Microsoft Office 提供COM接口 使用实例

下面是一个使用C语言调用Microsoft Excel的COM接口的实例：

#include <windows.h>
#include <objbase.h>
#include <stdio.h>
#include <conio.h>

// 定义Excel应用程序和工作簿对象
IDispatch *pExcelApp = NULL, *pWorkbook = NULL;
// 定义Excel工作表对象
IDispatch *pWorksheet = NULL;

int main()
{
    HRESULT hr;
    CLSID clsid;
    DISPID dispid;
    VARIANT result;
    DISPPARAMS params;
    EXCEPINFO excepInfo;
    BSTR bstr;

    // 初始化COM库
    CoInitialize(NULL);

    // 创建Excel应用程序对象
    hr = CLSIDFromProgID(L"Excel.Application", &clsid);
    hr = CoCreateInstance(&clsid, NULL, CLSCTX_LOCAL_SERVER, &IID_IDispatch, (void **)&pExcelApp);

    // 显示Excel应用程序窗口
    params.cArgs = 1;
    params.rgvarg = (VARIANTARG*)malloc(sizeof(VARIANTARG) * params.cArgs);
    params.rgvarg[0].vt = VT_BOOL;
    params.rgvarg[0].boolVal = TRUE;
    params.cNamedArgs = 1;
    params.rgdispidNamedArgs = (DISPID*)malloc(sizeof(DISPID) * params.cNamedArgs);
    bstr = SysAllocString(L"Visible");
    hr = pExcelApp->GetIDsOfNames(IID_NULL, &bstr, 1, LOCALE_SYSTEM_DEFAULT, &dispid);
    params.rgdispidNamedArgs[0] = dispid;
    hr = pExcelApp->Invoke(dispid, IID_NULL, LOCALE_SYSTEM_DEFAULT, DISPATCH_PROPERTYPUT, &params, NULL, &excepInfo, NULL);

    // 打开工作簿
    params.cArgs = 1;
    params.rgvarg = (VARIANTARG*)malloc(sizeof(VARIANTARG) * params.cArgs);
    params.rgvarg[0].vt = VT_BSTR;
    params.rgvarg[0].bstrVal = SysAllocString(L"C:\\example.xlsx");
    params.cNamedArgs = 1;
    params.rgdispidNamedArgs = (DISPID*)malloc(sizeof(DISPID) * params.cNamedArgs);
    bstr = SysAllocString(L"FileName");
    hr = pExcelApp->GetIDsOfNames(IID_NULL, &bstr, 1, LOCALE_SYSTEM_DEFAULT, &dispid);
    params.rgdispidNamedArgs[0] = dispid;
    hr = pExcelApp->Invoke(dispid, IID_NULL, LOCALE_SYSTEM_DEFAULT, DISPATCH_METHOD, &params, NULL, &excepInfo, NULL);
    hr = pExcelApp->GetIDsOfNames(IID_NULL, &bstr, 1, LOCALE_SYSTEM_DEFAULT, &dispid);
    hr = pExcelApp->Invoke(dispid, IID_NULL, LOCALE_SYSTEM_DEFAULT, DISPATCH_PROPERTYGET, &params, &result, &excepInfo, NULL);
    pWorkbook = result.pdispVal;

    // 获取工作表对象
    params.cArgs = 1;
    params.rgvarg = (VARIANTARG*)malloc(sizeof(VARIANTARG) * params.cArgs);
    params.rgvarg[0].vt = VT_I4;
    params.rgvarg[0].lVal = 1;
    params.cNamedArgs = 1;
    params.rgdispidNamedArgs = (DISPID*)malloc(sizeof(DISPID) * params.cNamedArgs);
    bstr = SysAllocString(L"Item");
    hr = pWorkbook->GetIDsOfNames(IID_NULL, &bstr, 1, LOCALE_SYSTEM_DEFAULT, &dispid);
    params.rgdispidNamedArgs[0] = dispid;
    hr = pWorkbook->Invoke(dispid, IID_NULL, LOCALE_SYSTEM_DEFAULT, DISPATCH_PROPERTYGET, &params, &result, &excepInfo, NULL);
    pWorksheet = result.pdispVal;

    // 修改单元格值
    params.cArgs = 2;
    params.rgvarg = (VARIANTARG*)malloc(sizeof(VARIANTARG) * params.cArgs);
    params.rgvarg[1].vt = VT_I4;
    params.rgvarg[1].lVal = 1;
    params.rgvarg[0].vt = VT_I4;
    params.rgvarg[0].lVal = 1;
    params.cNamedArgs = 0;
    bstr = SysAllocString(L"Cells");
    hr = pWorksheet->GetIDsOfNames(IID_NULL, &bstr, 1, LOCALE_SYSTEM_DEFAULT, &dispid);
    hr = pWorksheet->Invoke(dispid, IID_NULL, LOCALE_SYSTEM_DEFAULT, DISPATCH_PROPERTYGET, &params, &result, &excepInfo, NULL);
    IDispatch *pCell = result.pdispVal;
    params.cArgs = 1;
    params.rgvarg = (VARIANTARG*)malloc(sizeof(VARIANTARG) * params.cArgs);
    params.rgvarg[0].vt = VT_BSTR;
    params.rgvarg[0].bstrVal = SysAllocString(L"Hello World!");
    params.cNamedArgs = 1;
    params.rgdispidNamedArgs = (DISPID*)malloc(sizeof(DISPID) * params.cNamedArgs);
    bstr = SysAllocString(L"Value");
    hr = pCell->GetIDsOfNames(IID_NULL, &bstr, 1, LOCALE_SYSTEM_DEFAULT, &dispid);
    params.rgdispidNamedArgs[0] = dispid;
    hr = pCell->Invoke(dispid, IID_NULL, LOCALE_SYSTEM_DEFAULT, DISPATCH_PROPERTYPUT, &params, NULL, &excepInfo, NULL);

    // 保存工作簿并关闭Excel应用程序
    params.cArgs = 0;
    params.cNamedArgs = 0;
    bstr = SysAllocString(L"Save");
    hr = pWorkbook->GetIDsOfNames(IID_NULL, &bstr, 1, LOCALE_SYSTEM_DEFAULT, &dispid);
    hr = pWorkbook->Invoke(dispid, IID_NULL, LOCALE_SYSTEM_DEFAULT, DISPATCH_METHOD, &params, NULL, &excepInfo, NULL);
    bstr = SysAllocString(L"Close");
    hr = pWorkbook->GetIDsOfNames(IID_NULL, &bstr, 1, LOCALE_SYSTEM_DEFAULT, &dispid);
    hr = pWorkbook->Invoke(dispid, IID_NULL, LOCALE_SYSTEM_DEFAULT, DISPATCH_METHOD, &params, NULL, &excepInfo, NULL);
    bstr = SysAllocString(L"Quit");
    hr = pExcelApp->GetIDsOfNames(IID_NULL, &bstr, 1, LOCALE_SYSTEM_DEFAULT, &dispid);
    hr = pExcelApp->Invoke(dispid, IID_NULL, LOCALE_SYSTEM_DEFAULT, DISPATCH_METHOD, &params, NULL, &excepInfo, NULL);

    // 释放COM对象和内存
    pExcelApp->Release();
    pWorkbook->Release();
    pWorksheet->Release();
    pCell->Release();
    SysFreeString(bstr);
    CoUninitialize();

    return 0;
}

这个例子演示了如何创建Excel应用程序对象并打开一个工作簿，然后修改第一个单元格的值，并保存工作簿并关闭Excel应用程序。