将通用值复制到无符号char数组，然后用C ++复制回来

Question

I have a class in C++ that represents a buffer where I can store unsigned char . I have two methods, one the add generic values using templates and another to retrieve the values. When I am trying to retrieve the values I am getting Segmentation fault (core dumped) . I am using memcpy If I change to use std::copy(value, value, _valueChar); I get other errors: error: no type named 'value_type' in 'struct std::iterator_traits<int>'

#include <iostream>
#include <cstring>
#include <utility>
#include <vector>
#include <string>

class SkinnyBuffer {
private:
    unsigned char *_valueChar;
    std::size_t _sizeChar;
public:
    SkinnyBuffer();
    SkinnyBuffer(std::size_t size);
    ~SkinnyBuffer();
    void clean();

    template<typename T>
    void addValue(T value) {
        if (_valueChar != nullptr) {
            delete[] _valueChar;
        }
        // _sizeChar = n; // assume _size is a field
        // _valueChar = new unsigned char[_sizeChar];
        // std::copy(value, value, _valueChar);
        memcpy(_valueChar, &value, sizeof(value));
    }

    template<typename T>
    void addValue(std::size_t offset, T value) {
        if (_valueChar != nullptr) {
            delete[] _valueChar;
        }
        // _sizeChar = n; // assume _size is a field
        // _valueChar = new unsigned char[_sizeChar];
        // std::copy(value, value + offset, _valueChar);
        memcpy(_valueChar + offset, &value, sizeof(value));
    }

    unsigned char *getValue() {
        return _valueChar;
    }
};
#include "SkinnyBuffer.h"

SkinnyBuffer::SkinnyBuffer() {
}

SkinnyBuffer::SkinnyBuffer(std::size_t size) {
    _sizeChar = size;
    _valueChar = new unsigned char[_sizeChar];
}

SkinnyBuffer::~SkinnyBuffer() {
}

void SkinnyBuffer::clean() {
    _valueChar = new unsigned char[_sizeChar];
}

int main(int argc, char *argv[]) {

    int value = 50;
    int offset = sizeof(value);
    SkinnyBuffer b(offset);
    b.addValue(value);

    int dValue;
    memcpy(&dValue, b.getValue(), offset);
    std::cout << dValue << std::endl;
}

Answer 1

In addValue you explicitly delete the _valueChar buffer. Then the next line along you write into the deleted buffer. What did you expect this code to do?

This is the first of many issues in your code regarding memory management.

Just use a std::vector and as long as its big enough you wont have any of those issues.