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问题[c++]

Martin Hope
Timich
Asked: 2025-02-10 01:31:26 +0800 CST
  • 3

我正在练习使用OpenGL，并且面临的任务是实现向不同对象（在我的情况下，是由顶点组成的网格）添加多个不同纹理的能力。我知道您可以使用GL_TEXTURE0 + i，其中是从 0 到 31 的i数字。但是这里有一个限制，我只能使用 32 个纹理（而我需要更多）。另外，我还实现了实例化，这也为编写程序增加了细微差别（因此，我无法在渲染之前使用每个单独的网格切换到必要的纹理）。请告诉我如何成功实现我所需要的？glActiveTexture

c++
Martin Hope
Mikhail Medvedev
Asked: 2025-02-05 04:12:54 +0800 CST
  • 6

在创建一类二维矩阵时遇到了这个问题：

错误：

  1. E0461 非常量参数引用的初始值必须是左值

  2. C2440 返回：无法将“Matrix::MatrixRow”转换为“double &”

意思很清楚：Matrix 类中的运算符 [] 返回指向其中一行的指针，然后 MatrixRow 类中的运算符 [] 从数组中返回元素本身。实际上，下面这段代码是 Chat GPT 写给我的，因为这是我第一次遇到这样的语法，我只是想知道我到底做错了什么。我在 stack overflow western 上找到了一篇有此错误的文章，但我不知道如何将此解决方案应用于我的示例 https://stackoverflow.com/questions/55083497/c-cannot-convert-input-param-to-reference中的错误

class MatrixRow{
public:
   MatrixRow(double* matrixRow) : matrixRow(matrixRow) {}
   double& operator[](int index){
      return matrixRow[index];
   }
private:
   double* matrixRow;
};

class Matrix{
   MatrixRow& operator[](int index){
      return MatrixRow(matrix_arr[index]);
   } 
private:
   double** matrix_arr; 
};
c++
Martin Hope
Morphezy
Asked: 2025-02-03 05:41:48 +0800 CST
  • 9

我写了以下代码：

#include <string>
std::string fakeBin(std::string str){
    for (int i = 0; i < str.length(); i++){
        str[i] = ((str[i] - '0') > 4) ? '1' : '0';
    }
    return str;
}

它完成了它的工作，但我在写作时遇到了一个问题，这变得很有趣。如果? '1' : '0'用双引号替换引号，代码将停止工作。这是什么原因？C++ 中的单引号和双引号有什么区别？

c++
Martin Hope
CriticalError
Asked: 2025-01-30 02:38:01 +0800 CST
  • 5

问题是这样的：有一个服务器和一个客户端，我们通过套接字发送数据。例如，如果我在一台计算机上运行服务器和客户端，那么一切都很好，但如果我在一台计算机上运行服务器，在同一个网络上的另一台计算机上运行客户端，那么我也会收到响应并发送数据，但我收到的数据是 0，尽管在服务器端的调试器中一切都很好

客户

#define _WINSOCK_DEPRECATED_NO_WARNINGS
#include "Winsock2.h"
#include <iostream>
#include <windows.h>
#include <string>
#include <ctime>
#pragma comment(lib, "WS2_32.lib")

using namespace std;

struct GETSINCHRO
{
    string cmd;
    int curvalue;
};

struct SETSINCHRO
{
    string cmd;
    int correction;
};

int main()
{
    setlocale(LC_CTYPE, "Russian");

    string IP = "127.0.0.1";

    int Tc = 1000;
    int Cc = 0;

    SYSTEMTIME tm;
    SYSTEMTIME localtm;
    GETSINCHRO getsincro;
    SETSINCHRO setsincro;
    ZeroMemory(&setsincro, sizeof(setsincro));
    ZeroMemory(&getsincro, sizeof(getsincro));
    getsincro.cmd = "SINC";
    getsincro.curvalue = 0;


    cout << "Клиент запущен" << endl;

    try
    {
        SOCKET cS;
        WSADATA wsaData;

        if (WSAStartup(MAKEWORD(2, 0), &wsaData) != 0)
            throw SetErrorMsgText("Startup: ", WSAGetLastError());

        if ((cS = socket(AF_INET, SOCK_DGRAM, NULL)) == INVALID_SOCKET)
            throw SetErrorMsgText("Socket: ", WSAGetLastError());

        SOCKADDR_IN serv;
        serv.sin_family = AF_INET;
        serv.sin_port = htons(2000);
        serv.sin_addr.s_addr = inet_addr(IP.c_str());
        int avgcorr = 0;
        int lensockaddr = sizeof(serv);
        sendto(cS, (char*)&getsincro, sizeof(getsincro), 0, (sockaddr*)&serv, sizeof(serv));
        recvfrom(cS, (char*)&setsincro, sizeof(setsincro), 0, (sockaddr*)&serv, &lensockaddr);
        getsincro.curvalue += setsincro.correction;

        int  tick_number = 1;
        while (tick_number < 11)
        {
            GetSystemTime(&tm);
            TIME_ZONE_INFORMATION tzInfo;
            GetTimeZoneInformation(&tzInfo);
            SystemTimeToTzSpecificLocalTime(&tzInfo, &tm, &localtm);
            sendto(cS, (char*)&getsincro, sizeof(getsincro), 0, (sockaddr*)&serv, sizeof(serv));
            recvfrom(cS, (char*)&setsincro, sizeof(setsincro), 0, (sockaddr*)&serv, &lensockaddr);

            Cc += Tc;

            cout << " Date and time " << localtm.wMonth << "/" << localtm.wDay << "/" << localtm.wYear << " " << endl
                << localtm.wHour << " Hours " << localtm.wMinute << " Minutes " << localtm.wSecond << " Seconds " << localtm.wMilliseconds
                << " Milliseconds " << endl << tick_number++ << " " << getsincro.curvalue 
                << " Correction = " << setsincro.correction << endl;


            Sleep(Tc);
        }

    }
    catch (string errorMsgText)
    {
        cout << endl << errorMsgText << endl;
    }
    system("pause");

    return 0;
}

服务器

#include <iostream>
#include "Winsock2.h"
#include "ws2tcpip.h"
#include "string.h"
#include "locale"
#include "time.h"
#include "numeric"
#include <windows.h>
#include "ServerU.h"

#pragma comment(lib, "WS2_32.lib")

using namespace std;


struct SETSINCRO
{
    string cmd;
    int correction;
};

struct GETSINCRO
{
    string cmd;
    int curvalue;
};


int setAverageCorrection(int averageCorrection[], int length)
{
    return std::accumulate(averageCorrection, averageCorrection + length, 0);
}

int main()
{
    setlocale(LC_ALL, "Russian");

    SETSINCRO setsincro;
    GETSINCRO getsincro;
    ZeroMemory(&setsincro, sizeof(setsincro));
    ZeroMemory(&getsincro, sizeof(getsincro));

    setsincro.cmd = "SINCRO";
    setsincro.correction = 0;
    SYSTEMTIME tm;
    SYSTEMTIME localtm;


    cout << "Сервер запущен" << endl;

    try
    {
        SOCKET sS;
        WSADATA wsaData;


        if (WSAStartup(MAKEWORD(2, 0), &wsaData) != 0)
            throw SetErrorMsgText("Startup: ", WSAGetLastError());

        if ((sS = socket(AF_INET, SOCK_DGRAM, NULL)) == INVALID_SOCKET)
            throw SetErrorMsgText("Socket: ", WSAGetLastError());

        SOCKADDR_IN serv;
        serv.sin_family = AF_INET;
        serv.sin_port = htons(2000);
        serv.sin_addr.s_addr = INADDR_ANY;

        if (bind(sS, (LPSOCKADDR)&serv, sizeof(serv)) == SOCKET_ERROR)
            throw SetErrorMsgText("Bind_Server: ", WSAGetLastError());

        int count = 1;

        while (true)
        {
            SOCKADDR_IN client;
            int lc = sizeof(client);
            int average = 0;
            GetSystemTime(&tm);
            TIME_ZONE_INFORMATION tzInfo;
            GetTimeZoneInformation(&tzInfo);
            SystemTimeToTzSpecificLocalTime(&tzInfo, &tm, &localtm);
            recvfrom(sS, (char*)&getsincro, sizeof(getsincro), NULL, (sockaddr*)&client, &lc);
            c = clock();
            setsincro.correction = c - getsincro.curvalue;
            averageCorrection[count - 1] = setsincro.correction;
            average = setAverageCorrection(averageCorrection, count);
            sendto(sS, (char*)&setsincro, sizeof(setsincro), 0, (sockaddr*)&client, sizeof(client));


            char clientIp[INET_ADDRSTRLEN];
            inet_ntop(AF_INET, &(client.sin_addr), clientIp, INET_ADDRSTRLEN);
            cout << endl << count << "." << " Date and time " << localtm.wMonth << "/" << localtm.wDay << "/" << localtm.wYear//
                << " " << endl << localtm.wHour << " Hours " << localtm.wMinute << " Minutes " << localtm.wSecond//
                << " Seconds " << localtm.wMilliseconds << " Milliseconds " << endl << "Correction = " << setsincro.correction//
                << ", Average correction = " << average << endl;//
            cout << "Client's address " << clientIp << endl;//

            count++;
        }

    }
    catch (string errorMsgText)
    {
        cout << endl << errorMsgText;
    }

    return 0;
}
c++