問(wèn)題描述

在 C++ 中將字符串轉(zhuǎn)換為十六進(jìn)制以及反之的最佳方法是什么?

What is the best way to convert a string to hex and vice versa in C++?

示例:

• 像 "Hello World" 這樣的字符串轉(zhuǎn)成十六進(jìn)制格式:48656C6C6F20576F726C64
• 從十六進(jìn)制 48656C6C6F20576F726C64 到字符串:"Hello World"

• A string like "Hello World" to hex format: 48656C6C6F20576F726C64
• And from hex 48656C6C6F20576F726C64 to string: "Hello World"

推薦答案

像Hello World"這樣的字符串到十六進(jìn)制格式:48656C6C6F20576F726C64.

A string like "Hello World" to hex format: 48656C6C6F20576F726C64.

啊，給你:

#include <string>

std::string string_to_hex(const std::string& input)
{
    static const char hex_digits[] = "0123456789ABCDEF";

    std::string output;
    output.reserve(input.length() * 2);
    for (unsigned char c : input)
    {
        output.push_back(hex_digits[c >> 4]);
        output.push_back(hex_digits[c & 15]);
    }
    return output;
}

#include <stdexcept>

int hex_value(unsigned char hex_digit)
{
    static const signed char hex_values[256] = {
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
         0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1,
        -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    };
    int value = hex_values[hex_digit];
    if (value == -1) throw std::invalid_argument("invalid hex digit");
    return value;
}

std::string hex_to_string(const std::string& input)
{
    const auto len = input.length();
    if (len & 1) throw std::invalid_argument("odd length");

    std::string output;
    output.reserve(len / 2);
    for (auto it = input.begin(); it != input.end(); )
    {
        int hi = hex_value(*it++);
        int lo = hex_value(*it++);
        output.push_back(hi << 4 | lo);
    }
    return output;
}

(這里假設(shè)一個(gè)字符有 8 位，所以它不是很便攜，但你可以從這里獲取它.)

(This assumes that a char has 8 bits, so it's not very portable, but you can take it from here.)

這篇關(guān)于C++將字符串轉(zhuǎn)換為十六進(jìn)制，反之亦然的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！