c++ - 必须输入两次值才能工作 C++

Question

#include <iostream>
#include <limits>
#include <math.h>

using namespace std;

int main()
{
    float startTemperature;
    float endTemperature;
    float loopTemperature;
    float stepSize;
    float i;
    float numberOne;
    cout << "Please enter a start temperature: " << endl;;
    cin >> startTemperature;
    while(!(cin >> startTemperature)){
        cin.clear();

        cout << "Invalid input.  Try again: ";
    }
    cout << "Please enter an end temperature: ";
    cin >> endTemperature;
    while(!(cin >> endTemperature)) {
        cin.clear();
        cin.ignore(256, '\n');
        cout << "Invalid temperature. Please try again: ";
    }
    cout << "Please enter a step size: ";
    cin >> stepSize;
    while(!(cin >> stepSize)) {
        cin.clear();
        cin.ignore(256, '\n');
    }
    for(i = startTemperature; i < endTemperature; i += stepSize) {
        if(i == startTemperature) {
            cout << "Celsius" << endl;
            cout << "-------" << endl;
            cout << startTemperature << endl;
            loopTemperature = startTemperature + stepSize;
        }
        loopTemperature += stepSize;
        if(loopTemperature > 20) {
            break;
        }
        cout << loopTemperature << endl;
    }
}

您好，此代码的问题是我必须输入两次温度值。我看过其他答案，我认为这与 cin 缓冲区有关，但我不知道到底出了什么问题。

Answer 1

行内

cin >> startTemperature;  // <---problem here
while(!(cin >> startTemperature)){
    cin.clear();

    cout << "Invalid input.  Try again: ";
}

您正在输入一次，然后在循环中再次输入。这就是为什么您必须输入两次。

只需删除第一行输入，endTemparature 和 stepSize 也是如此。