如何在C++中将十六进制数转换为二进制？

#include <iostream>
#include <bitset>
#include <string>

int main() {
    std::string hex = "1A3F"; // 示例十六进制数
    unsigned int decimal;

    // 将十六进制字符串转换为十进制整数
    std::stringstream ss;
    ss << std::hex << hex;
    ss >> decimal;

    // 使用bitset转换为二进制
    std::bitset<32> binary(decimal); // 32位表示
    std::string binaryStr = binary.to_string();

    // 移除前导零
    size_t first_one = binaryStr.find('1');
    if (first_one != std::string::npos) {
        binaryStr = binaryStr.substr(first_one);
    } else {
        binaryStr = "0"; // 如果全是零
    }

    std::cout << "十六进制数 " << hex << " 转换为二进制为 " << binaryStr << std::endl;

    return 0;
}

十六进制数 1A3F 转换为二进制为 1101000111111

#include <iostream>
#include <string>
#include <unordered_map>

std::string hexToBinary(const std::string& hex) {
    // 十六进制字符到四位二进制的映射
    std::unordered_map<char, std::string> hexMap = {
        {'0', "0000"}, {'1', "0001"}, {'2', "0010"}, {'3', "0011"},
        {'4', "0100"}, {'5', "0101"}, {'6', "0110"}, {'7', "0111"},
        {'8', "1000"}, {'9', "1001"}, {'A', "1010"}, {'B', "1011"},
        {'C', "1100"}, {'D', "1101"}, {'E', "1110"}, {'F', "1111"},
        {'a', "1010"}, {'b', "1011"}, {'c', "1100"}, {'d', "1101"},
        {'e', "1110"}, {'f', "1111"}
    };

    std::string binary = "";
    for(char c : hex){
        if(hexMap.find(c) != hexMap.end()){
            binary += hexMap[c];
        }
        else{
            // 处理无效字符
            std::cerr << "无效的十六进制字符: "<< c << std::endl;
            return "";
        }
    }

    // 移除前导零
    size_t first_one = binary.find('1');
    if(first_one != std::string::npos){
        binary = binary.substr(first_one);
    }
    else{
        binary = "0";
    }

    return binary;
}

int main(){
    std::string hex = "1A3F";
    std::string binary = hexToBinary(hex);
    std::cout << "十六进制数 " << hex << " 转换为二进制为 " << binary << std::endl;
    return 0;
}

十六进制数 1A3F 转换为二进制为 1101000111111

#include <iostream>
#include <string>
#include <bitset>

std::string hexToBinary(const std::string& hex) {
    // 将十六进制字符串转换为整数
    unsigned int num;
    std::stringstream ss;
    ss << std::hex << hex;
    ss >> num;

    // 使用bitset转换
    std::bitset<32> bits(num);
    std::string binary = bits.to_string();

    // 移除前导零
    size_t first_one = binary.find('1');
    if(first_one != std::string::npos){
        binary = binary.substr(first_one);
    }
    else{
        binary = "0";
    }

    return binary;
}

int main(){
    std::string hex = "FF";
    std::string binary = hexToBinary(hex);
    std::cout << "十六进制数 " << hex << " 转换为二进制为 " << binary << std::endl;
    return 0;
}

十六进制数 FF 转换为二进制为 11111111