Listing serial ports on Windows

Question

Header

#pragma once

#include <windows.h>
#include <iostream>
#include <stdlib.h>
#include <WinBase.h>

using namespace std;

class SerialPort {
    public:
        BOOL COM_exists(int port);
};

cpp

#include "stdafx.h"
#include <string.h>
#include "SerialPort.h"

using namespace std;

BOOL SerialPort::COM_exists(int port)
{
    char buffer[7];
    COMMCONFIG CommConfig;
    DWORD size;

    if (!(1 <= port && port <= 255))
    {
        return FALSE;
    }

    snprintf(buffer, sizeof buffer, "COM%d", port);
    size = sizeof CommConfig;

    // COM port exists if GetDefaultCommConfig returns TRUE
    // or changes <size> to indicate COMMCONFIG buffer too small.
    return (GetDefaultCommConfig(L"buffer", &CommConfig, &size)
        || size > sizeof CommConfig);
}

main

#include "stdafx.h"
#include <iostream>
#include "SerialPort.h"

using namespace std;


if(num==1)
    {
        int i;
        for (i = 1; i < 256; ++i)
        {
            if (COM_exists(i))
            {
                cout <<"COM%d \n";
            }
        }
    }

I want listing serial ports on Windows ,but I'm having a hard time. Help me list the serial ports. error code = c3861 ,e0020

I want listing serial ports on windows. The end of the road ,Select a serial port that can be connected to enable communication. please help me

Reopened because the suggested duplicate did not deal with the issues in the posted code (which have nothing to do with COM ports). — john, Nov 09 '22 at 08:05

john · Answer 1 · 2022-11-09T08:16:27.000

Main problem is here

if(num==1)
    {
        int i;
        for (i = 1; i < 256; ++i)
        {
            if (COM_exists(i))
            {
                cout <<"COM%d \n";
            }
        }
    }

In C++ code has to go in functions (a simplification but good enough for now) and the program starts with a special function called main. Also cout <<"COM%d \n"; is not the correct way to print a COM port, I've used the correct way in the code below. Also in the code above what is num supposed to be?

Anyway rewrite as follows and you're a little closer

    int main() // start of program
    {
        int i;
        for (i = 1; i < 256; ++i)
        {
            if (COM_exists(i))
            {
                cout << "COM " << i << "\n";
            }
        }
    }

There are other problems such as the pointless SerialPort class. I would just remove that.

Replace

class SerialPort {
    public:
        BOOL COM_exists(int port);
};

with

BOOL COM_exists(int port);

and

BOOL SerialPort::COM_exists(int port)

with

BOOL COM_exists(int port)

The code looks like you are trying to learn C++ by cutting and pasting code from the internet. That is never going to work, C++ is a complex language and really needs formal study to be learned effectively. Here's a curated list of C++ books.

Listing serial ports on Windows

1 Answers1