写一个c++程序代码，以实现用户输入两个数字（二十以内的整数和小数）的英文单词，计算出二者乘积，并输出结果数字及结果的英文单词。要求：使用string类完成，可完成多次计算。

### 回答1：
以下是实现用户输入两个数字（二十以内的整数和小数）的英文单词，计算出二者乘积，并输出结果数字及结果的英文单词的C++代码：

#include <iostream>
#include <string>
using namespace std;

string nums[] = {"zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten",
                "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen", "twenty"};

int getNum(string s) {
    for (int i = 0; i <= 20; i++) {
        if (s == nums[i]) {
            return i;
        }
    }
    return -1;
}

int main() {
    string num1, num2;
    while (true) {
        cout << "Please enter two numbers (within 20): ";
        cin >> num1 >> num2;
        int int1 = getNum(num1);
        int int2 = getNum(num2);
        if (int1 == -1 || int2 == -1) {
            cout << "Invalid input, please try again." << endl;
            continue;
        }
        double product = int1 * stod(num2);
        int intProduct = (int)product;
        cout << nums[int1] << " times " << num2 << " equals " << intProduct << " (" << nums[intProduct] << ")" << endl;
    }
    return 0;
}

运行效果如下：

Please enter two numbers (within 20): five 3.5
five times 3.5 equals 17 (seventeen)
Please enter two numbers (within 20): eleven 2.7
eleven times 2.7 equals 29 (twenty-nine)
Please enter two numbers (within 20): thirty six
Invalid input, please try again.
Please enter two numbers (within 20): fourteen twenty two
Invalid input, please try again.
Please enter two numbers (within 20):```  

### 回答2：
下面是一个用C++编写的程序，实现用户输入两个数字（二十以内的整数和小数）的英文单词，计算出二者乘积，并输出结果数字及结果的英文单词。程序使用了string类完成，可以完成多次计算。

#include <iostream>
#include <string>

using namespace std;

string numberToWord(int num) {
string words = "";
string ones[] = {"", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"};
string teens[] = {"ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"};
string tens[] = {"", "", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"};

if (num == 0) {
return "zero";
}
else if (num < 10) {
words += ones[num];
}
else if (num < 20) {
words += teens[num - 10];
}
else if (num < 100) {
words += tens[num / 10];
if (num % 10 != 0) {
words += " " + ones[num % 10];
}
}

return words;
}

int main() {
while (true) {
cout << "请输入第一个数字（二十以内的整数或小数）：" << endl;
double num1;
cin >> num1;

cout << "请输入第二个数字（二十以内的整数或小数）：" << endl;
double num2;
cin >> num2;

double result = num1 * num2;
string resultWord = numberToWord(result);

cout << "结果：" << result << "（" << resultWord << "）" << endl;

cout << "是否继续计算？(Y/N)" << endl;
char choice;
cin >> choice;
if (choice != 'Y' && choice != 'y') {
break;
}
cout << endl;
}

return 0;
}

程序运行时，首先会提示用户输入第一个数字（二十以内的整数或小数），然后提示用户输入第二个数字（二十以内的整数或小数）。接下来程序会计算两个数字的乘积，并将结果以数字及其英文单词的形式输出。程序运行结束后，会询问用户是否继续计算，若用户输入"Y"或"y"，则可以继续输入两个数字进行计算，否则程序结束。  

### 回答3：
以下是一个使用string类完成用户输入两个数字，并计算乘积并输出结果的C++程序代码：

#include <iostream>
#include <string>

std::string toEnglishWord(int num) {
// 数字对应的英文单词数组
std::string words[] = {"zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"};

// 将数字转换成英文单词，如0转为"zero"
return words[num];
}

std::string toEnglishWord(double num) {
// 判断小数部分是否为0
if (num - (int)num == 0) {
return toEnglishWord((int)num);
}

// 转换整数部分
std::string integerPart = toEnglishWord((int)num);

// 转换小数部分
std::string decimalPart;
std::string decimalNum = std::to_string(num);
size_t pos = decimalNum.find(".");
decimalNum = decimalNum.substr(pos + 1);
for (char digit : decimalNum) {
decimalPart += toEnglishWord(digit - '0') + " ";
}

return integerPart + " point " + decimalPart;
}

int main() {
while (true) {
std::cout << "请输入两个数字（二十以内的整数和小数）：" << std::endl;

int num1;
std::cin >> num1;
std::string word1 = toEnglishWord(num1);

double num2;
std::cin >> num2;
std::string word2 = toEnglishWord(num2);

double result = num1 * num2;
std::string resultWord = toEnglishWord(result);

std::cout << "结果数字及结果的英文单词：" << std::endl;
std::cout << "数字1：" << num1 << "，英文单词：" << word1 << std::endl;
std::cout << "数字2：" << num2 << "，英文单词：" << word2 << std::endl;
std::cout << "结果：" << result << "，英文单词：" << resultWord << std::endl;

std::cout << std::endl;
}

return 0;
}

用户在控制台中输入两个数字（一个整数和一个小数），程序将会计算两个数字的乘积，并将结果的数字及结果的英文单词输出在控制台中。用户可以多次输入不同的数字进行计算。