用c ++输入验证。 [英] Input validation in c++.

问题描述

下面是我的代码，程序正常工作，直到我输入除数字以外的任何内容。在分数的输入验证期间出现问题。

  #include   <   iostream  >  
   #include   <  < span class =code-leadattribute> iomanip  >  
  使用  namespace  std; 
 
  int  main（）
 {
  int  counter =  0 ; 
  double 得分，
 averagescore，
 totalscore =  0 。< span class =code-digit> 0 ; 
 
 cout<<  输入学生的分数，如果没有剩下的学生，则输入-1。\\ n ; 
 cin>>得分了; 
  while （得分<  -   1  ||得分>  100 ）
 {
 cout<<   \ n这不是一个有效的答案，请输入介于-1和100之间的百分比 ; 
 cin>>得分了; 
} 
 
  while （得分！=  -   1 ）
 {
 totalscore + =得分; 
 cout<<   \ n输入学生的分数，如果没有剩下的学生，则为-1。\ n; 
 cin>>得分了; 
  while （得分<  -   1  ||得分>  100 ）
 {
 cout<<   \ n这不是一个有效的答案，请输入介于-1和100之间的百分比 ; 
 cin>>得分了; 
} 
 counter ++; 
} 
 
 averagescore = totalscore / counter; 
 cout<<   \ n该课程的平均分为：<< averagescore<< ' ％'<< ENDL; 
} 

我的尝试：



我试着查看是否有任何逻辑错误，即使我多次查看也没有找到我。我假设这是一个逻辑错误，但我不知道该怎么做才能使它输入验证只接受介于-1和100之间的数字。

解决方案

< blockquote>请参阅：讲义 - cin.fail（），cin.clear（），cin.eof （）和strchr（） [ ^ ] - 使用 cin.fail 检查用户是否输入了有效数字，或者例如单词Hello。

Below is my code and the program works fine until I enter anything other than a number. The problem occurs during the input validation of score.

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

int main()
{
    int counter = 0;
    double score,
           averagescore,
           totalscore = 0.0;

    cout << "Enter the score of a student, or -1 if no more students are left.\n";
    cin >> score;
    while (score < -1 || score > 100)
    {
        cout << "\nThat is not a valid answer please enter a percent between -1 and 100\n";
        cin >> score;
    }

    while (score != -1)
    {
        totalscore += score;
        cout << "\nEnter the score of a student, or -1 if no more students are left.\n";
        cin >> score;
        while (score < -1 || score > 100)
        {
            cout << "\nThat is not a valid answer please enter a percent between -1 and 100\n";
            cin >> score;
        }
        counter++;
    }

    averagescore = totalscore / counter;
    cout << "\nThe average score of the class is: " << averagescore << '%' << endl;
}

What I have tried:

I tried looking through to see if there were any logic errors and none came to me even though I looked through several times. I'm assuming this is a logic error, but I am not sure what I should do to make it so this input validation only accepts numbers between -1 and 100.

解决方案

See here: Lecture Notes - cin.fail(), cin.clear(), cin.eof() and strchr()[^] - use cin.fail to check if the user entered a valid number at all, or the word "Hello" for example.

这篇关于用c ++输入验证。的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！