[WebMethod]
public string TestMethod(string input)
{
return "Hello World"+input;
}
My C++ code is as:
#include <stdio.h>
#import "msxml4.dll" 
using namespace MSXML2;
 
#import "C:\Program Files\Common Files\MSSoap\Binaries\MSSOAP30.dll" \
exclude("IStream", "ISequentialStream", "_LARGE_INTEGER", "_ULARGE_INTEGER", "tagSTATSTG", "_FILETIME")
using namespace MSSOAPLib30;
 
ISoapSerializerPtr Serializer;
ISoapReaderPtr Reader;
ISoapConnectorPtr Connector;
// Connect to the service
Connector.CreateInstance(__uuidof(HttpConnector30));
Connector->Property["EndPointURL"] = "http://localhost/WS/Service1.asmx";
Connector->Connect();
// Begin message
Connector->Property["SoapAction"] = "http://tempuri.org/TestMethod";
Connector->BeginMessage();
// Create the SoapSerializer
Serializer.CreateInstance(__uuidof(SoapSerializer30));
// Connect the serializer to the input stream of the connector
Serializer->Init(_variant_t((IUnknown*)Connector->InputStream));
// Build the SOAP Message
Serializer->StartEnvelope("","","");
Serializer->StartBody("");
Serializer->StartElement("TestMethod","http://tempuri.org/TestMethod","","m");
Serializer->StartElement("input","","","");
Serializer->WriteString("input");
Serializer->EndElement();
Serializer->EndElement();
Serializer->EndBody();
Serializer->EndEnvelope();
 
// Send the message to the web service
Connector->EndMessage(); 
// Let us read the response
Reader.CreateInstance(__uuidof(SoapReader30));
// Connect the reader to the output stream of the connector
Reader->Load(_variant_t((IUnknown*)Connector->OutputStream), "");
// Display the result
printf("Answer: %s\n", (const char *)Reader->RpcResult->text);
_bstr_t res = Reader->RpcResult->text;