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C++的内存和布尔数组

pointers c++

-1

Gordon13 · 技术社区 · 7 年前

我有一段代码将一个字符串写入内存,我正试图修改它来编写一个布尔数组。

这个想法很简单,就是每次迭代都将随机布尔数据写入内存。

下面是编写字符串的方法示例:

void MemoryWriter::write(const string& data) {
    auto buffer = MapViewOfFile(m_shmHandler, FILE_MAP_ALL_ACCESS, 0, 0, m_memorySize);
    CopyMemory(buffer, data.c_str(), data.size());
}

下面是一个试图编写布尔值的非工作示例:

void MemoryWriter::write(const bool * data) {
    auto buffer = MapViewOfFile(m_shmHandler, FILE_MAP_ALL_ACCESS, 0, 0, m_memorySize);
    CopyMemory(buffer, data, data.size());
}

bool* MemoryWriter::createRandomArduinoPinData() const {
    bool data[12];
    for (size_t i = 0; i < m_memorySize; i++) {
        data[i] = getRandomBool();
        std::cout << "C++: RandomArduinoPinData " << data[i] << std::endl;
    }
    return data;
}

主要功能如下:

#include "stdafx.h"
#include "MemoryWriter.h"
#include <iostream>
#include <string>
#include <thread>


int main()
{
    std::wstring memoryName{ L"shm_1" };
    size_t memorySize{ 12 * sizeof(bool) };
    MemoryWriter writer(memoryName, memorySize);

    while (true) {
        bool* data;
        //data = writer.createRandomData();
        data = writer.createRandomArduinoPinData(); // <-- this generates the random bool array and is confirmed to work
        writer.write(data); <-- for some reason, this part doesn't receive the same array
        std::cout << "C++: Written in shm - " << data[0] << data[1] << data[2] << std::endl;
        std::this_thread::sleep_for(std::chrono::milliseconds(100));
    }

    return 0;
}

这里是控制台输出,显示正在生成的随机数据,以及输出的不同数据:

C++: RandomArduinoPinData 1
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 1
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 1
C++: RandomArduinoPinData 1
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 0
C++: Written in shm - 00AFFCE0
C++: RandomArduinoPinData 1
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 1
C++: RandomArduinoPinData 1
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 1
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 1
C++: Written in shm - 00AFFCE0
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 1
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 1
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 1
C++: RandomArduinoPinData 1
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 0
C++: RandomArduinoPinData 1
C++: Written in shm - 00AFFCE0

我想这可能是复写记忆的问题,但我不确定。指针和记忆仍然是我努力学习的东西,我很难解决这个问题。

有什么想法吗?

2 回复 | 直到 7 年前

Gordon13 7 年前

这个问题与指针的使用有关。createRandomArduInInData函数返回一个指向内部变量的指针,该变量在函数结束时被擦除,这意味着该函数的返回值始终是指向空内存地址的指针。代码现在使用std::vector代替。

已更新createRandomPinData函数:

std::vector<bool> MemoryWriter::createRandomArduinoPinData() const {
    std::vector<bool> data(12);
    for (size_t i = 0; i < m_memorySize; i++) {
        data[i] = getRandomBool();
        std::cout << "C++: RandomArduinoPinData " << data[i] << std::endl;
    }
    return data;
}

更新的写入函数:

void MemoryWriter::write(const std::vector<bool>& data) {
    auto buffer = MapViewOfFile(m_shmHandler, FILE_MAP_ALL_ACCESS, 0, 0, m_memorySize);
    CopyMemory(buffer, &data, data.size());
}

Ali Asadpoor 7 年前

random function returns the same value