测试数字是否具有不带任何库的十进制值

我需要测试C ++中数字是否具有十进制值.我只想使用< iostream> 而没有其他库，但是我很好奇我使用的方法是否可以接受.如果您能提供任何帮助，找到更好的方法，那将是很好的.

I need to test if a number has a decimal value in C++. I only want to use <iostream> and no other library, but I'm curious if the method I'm using would be acceptable. If you can offer any assistance finding a better way that would be great.

#include <iostream>
int main() {
    double x, y;
    std::cin >> x;
    int z = x;
    if (x - z != 0) {
        std::cout << "It's a decimal.";
    }
    else {
        std::cout << "It's not a decimal.";
    }
    return 0;
}

考虑了更长的时间后，我想出了一个新的函数，该函数似乎更容易接受.

Upon thinking about this longer, I came up with a new function that seems more acceptable.

double TestForDecimal(double Num) {
    double z;
    while (Num > 1) {
        if (Num > 101) /* Increments down to 1 more quickly */ {
        Num = Num - 100;
    }
        else if (Num > 12) { Num = Num - 10; }
        else { Num--; }
    }
    if (Num < 1 && Num > 0) {
        std::cout << "This number has a decimal value" << std::endl;
        return 1;
    }
    else {
        std::cout << "Theres no decimal" << std::endl;
        return 0;
    }
}