C++实现进制转换工具 数值计算与格式化输出

#include <iostream>
#include <string>
#include <algorithm>
#include <cctype>
#include <cmath>

// 十进制转任意进制（支持2~36）
std::string decimalToBase(long long n, int base) {
    if (base < 2 || base > 36) {
        return "错误：进制超出范围（2-36）";
    }

    if (n == 0) return "0";

    bool negative = false;
    if (n < 0) {
        negative = true;
        n = -n;
    }

    const std::string digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    std::string result;

    while (n > 0) {
        result += digits[n % base];
        n /= base;
    }

    if (negative) {
        result += '-';
    }

    std::reverse(result.begin(), result.end());
    return result;
}

// 任意进制转十进制（支持2~36）
long long baseToDecimal(const std::string& numStr, int base) {
    if (base < 2 || base > 36) {
        std::cerr << "错误：进制超出范围（2-36）\n";
        return 0;
    }

    long long result = 0;
    long long power = 1;
    const std::string digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    for (int i = numStr.size() - 1; i >= 0; --i) {
        char c = std::toupper(numStr[i]);
        int val = -1;

        for (int j = 0; j < digits.size(); ++j) {
            if (digits[j] == c) {
                val = j;
                break;
            }
        }

        if (val == -1 || val >= base) {
            std::cerr << "错误：字符 '" << c << "' 不符合 " << base << " 进制\n";
            return 0;
        }

        result += val * power;
        if (power > LLONG_MAX / base && i > 0) {
            std::cerr << "错误：数值溢出\n";
            return 0;
        }
        power *= base;
    }

    return result;
}

// 统一输出多种进制格式
void printConversions(long long decimalValue) {
    std::cout << "十进制: " << decimalValue << "\n";
    std::cout << "二进制: " << decimalToBase(decimalValue, 2) << "\n";
    std::cout << "八进制: " << decimalToBase(decimalValue, 8) << "\n";
    std::cout << "十六进制: " << decimalToBase(decimalValue, 16) << "\n";
    std::cout << "三十六进制: " << decimalToBase(decimalValue, 36) << "\n";
}

int main() {
    int choice;
    std::cout << "进制转换工具\n";
    std::cout << "1. 十进制转其他进制\n";
    std::cout << "2. 其他进制转十进制\n";
    std::cout << "3. 显示所有常见进制\n";
    std::cout << "请选择功能: ";
    std::cin >> choice;

    if (choice == 1) {
        long long dec;
        std::cout << "输入十进制数: ";
        std::cin >> dec;
        int base;
        std::cout << "输入目标进制 (2-36): ";
        std::cin >> base;
        std::cout << "结果: " << decimalToBase(dec, base) << "\n";
    }
    else if (choice == 2) {
        std::string num;
        int base;
        std::cout << "输入原进制数: ";
        std::cin >> num;
        std::cout << "输入原进制 (2-36): ";
        std::cin >> base;
        long long result = baseToDecimal(num, base);
        std::cout << "十进制结果: " << result << "\n";
    }
    else if (choice == 3) {
        long long dec;
        std::cout << "输入十进制数: ";
        std::cin >> dec;
        printConversions(dec);
    }
    else {
        std::cout << "无效选择\n";
    }

    return 0;
}

选择 3
输入十进制数: -42

十进制: -42
二进制: -101010
八进制: -52
十六进制: -2A
三十六进制: -16