C++ 将 HexString 转换为扩展的 Ascii 代码在文本文件中不显示正确的 ascii 代码

Question

How to convert hex string to extended ascii code symbol code and write the converted codes to the text file.

Example input string:

std:string strInput = "FF2139FF"

Example output string should be "ÿ.9ÿ" in the text file.

I tried to write the program as below to write to a text file.

#include <string>
using namespace std;

string ConvertHexStringToAsciiString(string sInputHexString, int step)
{
    int len = sInputHexString.length();
    string sOutputAsciiString;
    for (int i = 0; i < len; i += step)
    {
        string byte = sInputHexString.substr(i, step);
        char chr = (char)(int)strtol(byte.c_str(), nullptr, 16);
        sOutputAsciiString.push_back(chr);
    }
    return sOutputAsciiString;
}

void main()
{
    string sInputHexString = "FF2139FF";

    string sOutputAsciiString = "";
    sOutputAsciiString = ConvertHexStringToAsciiString(sInputHexString, 2);

    const char* sFileName = "E:\\MyProgramDev\\Convert_HexString_To_AsciiCode\\Convert_HexString_To_AsciiCode\\TestFolder\\1.txt";
    FILE* file = fopen(sFileName, "wt");
    if (nullptr != file)
    {
        fputs(sOutputAsciiString.c_str(), file);
        fclose(file);
    }
}

It seems working but when I open the text file 1.txt with notepad, I cannot see the ÿ and only.9 displayed? I am not sure how to display it correctly using notepad or my code is wrong?

Thanks.

Answer 1

Use better notepad - or even better, any hexeditor to view result.

Try for example XVI 32 hex editor

Answer 2

I found a way to do thing, Split this HexString FF to two BYTE(unsigned char) "F" and "F", and then construct together and convert to decimal. It can show the correct letter.