我需要一个适当的while条件来进行循环

Question

当我从Arduino收到整条消息时，这里有一个while循环，要满足一个条件。问题是：我不知道如何改变这种情况

do
{
     read_result = arduino.readSerialPort(incomingData, MAX_DATA_LENGTH);
     //prints out data
     if (read_result > 0)
         cout << incomingData;
     //puts(incomingData);
} while (true);

我从Here启发了我所有的项目

但是我改变了主要功能和我的arduino文件。这是我的主要功能：

//This code snippet will help you to read and write data from arduino
//#include "stdafx.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string>
#include "SerialClass.h"
#include <fstream>


//using namespace std;
using std::cin;
using std::cout;
using std::endl;

//String for getting the Output from Arduino
char outputData[MAX_DATA_LENGTH];
//String for incoming data
char incomingData[MAX_DATA_LENGTH];


//Portname must contain these backslashes
char *port_name = "\\\\.\\COM5";

const unsigned int bufSize =255;

int main()
{
    SerialPort arduino(port_name);
    if (arduino.isConnected())
        std::cout << "Connection Established! \n" << std::endl;
    else
        std::cout << "ERROR, check port!";

       while (arduino.isConnected()) {

            std::string input_string ;
            //cout << "Write something: \n";
            getline(cin, input_string);
            //Creating a c string
            char *c_string = new char[input_string.size() + 1];
            //copying the std::string to c string
            std::copy(input_string.begin(), input_string.end(), c_string);
            //Adding the delimeter
            c_string[input_string.size()] = '\n';
            //Writing string to arduino
            arduino.writeSerialPort(c_string, MAX_DATA_LENGTH);
            //Getting reply from arduino
            arduino.readSerialPort(outputData, MAX_DATA_LENGTH);
            //printing the output
            //puts(outputData);
            //freeing c_string memory
            delete[] c_string;





        //Check if data has been read or not

            int read_result;


        do
        {
             read_result = arduino.readSerialPort(incomingData, MAX_DATA_LENGTH);
             //prints out data
             if (read_result > 0)
                 cout << incomingData;
             //puts(incomingData);
        } while (true);

        //wait a bit
        //Sleep(100000);
       }


}

这是我的arduino文件：

int PButton=2;
int Led=13;
unsigned long start,finished,elapsed;


void setup() {
 Serial.begin(9600); //begins the Serial Connection.
 pinMode(PButton, INPUT_PULLUP);
 pinMode(Led,OUTPUT);
 digitalWrite(Led,LOW);
 Serial.println("Is the video already started? ""yes/no""...\n");
 start=millis();
  String ans;

   while(Serial.available()<=0)
   {
   }
       ans=Serial.readStringUntil('\n');    
       if(ans.equals("yes")){   
       digitalWrite(13,HIGH);
       Serial.println("The video is started!\n\nplease Press the Pushbutton when the task is fullfilled!\n");
      }
      else if(ans.equals("no")){
        digitalWrite(13,LOW);
        Serial.println("The Video is still not started! \n");  
      }


 }

void loop() {



       int buttonState=digitalRead(PButton);  //read the input pin
        if(buttonState==LOW)
        { 
        Serial.print("The pushbutton is  pressed after   ");
        finished=millis();
        elapsed=finished-start;
        Serial.println(elapsed);
        delay(3000);
         } 


}