验证功能

Question

我的问题是我如何验证getTestScore函数的数据？需要程序告诉用户invalid data, please enter a score in between 0 and 100，如果他们输入的是负数或超过100的数字。谢谢。

#include <iostream> 
using namespace std; 
//function prototypes 
float getTestScore(); 
float calcAverage(float score1, float score2, float score3); 
int main() 
{ 
    float s1, s2, s3; //these variables are used to store test scores 
    float average; 
    //call getTestScore function to get the test scores 
    s1 = getTestScore(); 
    s2 = getTestScore(); 
    s3 = getTestScore(); 
    //call calcAverage to calculate the average of three test scores 
    average = calcAverage(s1, s2, s3); 

    //display the average 
    cout << "average of three test scores(" << s1 << "," << s2 << "," << s3 <<  ")is"  << average << endl; 
    return 0; 
} 

//function definitions/implementation getTestScore function gets a test score from the user and 
//validates the score to make sure the value is between 0 and 100. if score is out of range 
//getTestScore function allows the user to re-enter the score. This function returns a valid score 
// to the caller function 
float getTestScore() 
{ 
    float score = 0; 
    do 
    { 
     cout << "Enter test score: " << endl; 
     cin >> score; 
    } while (!(score >= 0 && score <= 100)); 

    return score; 
} 

// calcAverage function calculates and returns the average of the three test scores passed to 
//the function as input. 
float calcAverage(float score1, float score2, float score3) 
{ 
    float average; 
    average = (score1 + score2 + score3)/3; 

    return average; 
} 

Answer 1

您可以更改while循环这样的：

float getTestScore() 
{ 
    float score = 0; 
    while ((cout << "Enter test score: ") 
        && (!(cin >> score) || score < 0 || score > 100)) { 
     // This part only gets executed on invalid input 
     cout << "invalid data, please enter a score in between 0 and 100 "; 
     cin.clear(); 
     cin.ignore(numeric_limits<streamsize>::max(), '\n'); 
    } 
    return score; 
} 

Answer 2

通过使用“Do-While”，在检查输入之前至少执行一次代码块。

第一个输入因此不会被你的病情检查：

while (!(score >= 0 && score <= 100)); 

使用标准while循环，因此检查前手这个条件应该可以解决你的问题。