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，就像这样{0x4D,x0FF,0x01}我把它放在一个无符号的字符数组中。 我可以打印我想储存的东西，但我无法在我的数组中储存数据。 我阅读了位集类文档，但我不确定它是否是我需要的。 根据这个源代码，我怎样才能存储读取的数据以获得与以下相同的结果：

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

请注意，向量没有好的符号，这就是我使用 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!nn";
}
// 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!nn";
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());
}