这个输入中float和double有什么区别？

Question

我有两个输入,唯一的区别是我在第二个输入中用"float"替换"double".但是,第一个可以按预期运行,但不能运行第二个.第二个不以0.1的输入结束.有谁对此有一些想法？非常感谢!

第一输入:

#include <iostream>

using namespace std;

int main()
{
    double input;
    input = 0;
    double sum = 0;
    cout << "Please enter a series numbers and end with 0.1: ";
    cin >> input;
    while (input != 0.1)
    {
        sum += input;
        cout << "The cumulative sum is: " << sum << endl;
        cin >> input;
    }
    return 0;
}


Please enter a series numbers and end with 0.1: 1 2 3 0.1
The cumulative sum is: 1
The cumulative sum is: 3
The cumulative sum is: 6

第二输入:

#include <iostream>
using namespace std;

int main()
{
    float input;
    input = 0;
    float sum = 0;
    cout << "Please enter a series numbers and end with 0.1: ";
    cin >> input;
    while (input != 0.1)
    {
        sum += input;
        cout << "The cumulative sum is: " << sum << endl;
        cin >> input;
    }
    return 0;
}


Please enter a series numbers and end with 0.1: 1 2 3 0.1
The cumulative sum is: 1
The cumulative sum is: 3
The cumulative sum is: 6
The cumulative sum is: 6.1

Answer 1

0.1在条件(input != 0.1)是double最接近理性1/10.在float最接近这种理性的,0.1f代表不同的值,并且不使这一情况属实.

如果要float在程序中使用,请使用(input != 0.1f)相应的条件.