如何使用setfill和setw在字符串变量中存储十六进制值

Question

我读取了一个文件并将其转换为十六进制表示法，例如{0x4D,x0FF,0x01}其存储在无符号char数组中。 我可以打印要存储的内容，但无法存储阵列中的数据。 我阅读了位集类文档，但不确定是否需要它。 根据此源代码，我该如何库存读取的数据具有与以下相同的结果：

unsigned char array[3] = {0x4D,x0FF,0x01};

请注意，向量没有很好的表示法，这就是为什么我使用setfill和setw的原因。

    size = file.tellg();
    unsigned char* rawData = new unsigned char[size];
    memblock = new uint8_t[size];
    std::vector<uint8_t> memblock(size);
    file.seekg(0, ios::beg);
    file.read(reinterpret_cast<char*>(memblock.data()), size);
    file.close();
    for (int i = 0; i < size; i = i++)
    {
        if (i == (int)size - 1)
        {
            cout << "0x" << setfill('0') << setw(2) << std::hex << (unsigned)memblock.at(i);
        }
        else
        {
            cout << "0x" << setfill('0') << setw(2) << std::hex << (unsigned)memblock.at(i) << ",";
        }

    }

编辑：这是我的实际代码：

    unsigned char* rawData[1] = {0x00}; // My rawData in out of function.

 void readFile(std::string p_parametre, unsigned char* rawData[])
{
    std::ifstream input{ p_parametre, std::ios::binary };
    if (!input.is_open()) {  // make sure the file could be opened
        std::cout << "Error: Couldn't open\"" << p_parametre << "\" for reading!\n\n";
    }

    // read the file into a vector
    std::vector<unsigned char> data{ std::istream_iterator<unsigned char>{ input },
                                     std::istream_iterator<unsigned char>{} };

    std::ostringstream oss;  // use a stringstream to format the data

                                 // instead of the glyph
    for (int i = 0; i < data.size(); i++)
    {
        if (i == i- 1)
        {
            oss <<'0'
                << 'x'
                << std::setfill('0') << std::setw(2) << uppercase << std::hex << static_cast<int>(data.at(i));
        }
        else
        {
            oss << '0'
                << 'x'
                << std::setfill('0') << std::setw(2) << uppercase << std::hex << static_cast<int>(data.at(i)) << ',';
        }

    }

    // create a unique_ptr and allocate memory large enough to hold the string:
    std::unique_ptr<unsigned char[]> memblock{ new unsigned char[oss.str().length() + 1] };

    // copy the content of the stringstream:
    int r = strcpy_s(reinterpret_cast<char*>(memblock.get()), oss.str().length() + 1, oss.str().c_str());

    OpenFile(memblock.get());
    getchar();
}

Answer 1

#include <cstdlib>
#include <vector>
#include <string>
#include <sstream>
#include <fstream>
#include <iostream>
#include <iomanip>
#include <iterator>
#include <memory>
#include <cstring>

int main()
{
    char const *input_filename{ "test.txt" };
    std::ifstream input{ input_filename, std::ios::binary };
    if (!input.is_open()) {  // make sure the file could be opened
        std::cout << "Error: Couldn't open\"" << input_filename << "\" for reading!\n\n";
        return EXIT_FAILURE;
    }

    // read the file into a vector
    std::vector<unsigned char> data{ std::istream_iterator<unsigned char>{ input },
                                     std::istream_iterator<unsigned char>{} };

    std::ostringstream oss;  // use a stringstream to format the data
    for (auto const &d : data)       // iterate over every element in vector data
        oss << std::setw(2)          // set the field-width to 2
            << std::setfill('0')     // fill up unused width with '0' instead space
            << std::hex              // output as hex number
            << static_cast<int>(d);  // cast the character to an int cause we
                                     // want to print the numeric representation
                                     // instead of the glyph

    // > Exact, I would like each byte as hex in my unsigned string array.

    // create a unique_ptr and allocate memory large enough to hold the string:
    std::unique_ptr<unsigned char[]> memblock{ new unsigned char[oss.str().length() + 1] };

    // copy the content of the stringstream:
    std::strcpy(reinterpret_cast<char*>(memblock.get()), oss.str().c_str());
}