Question

我正在开始教科书c ++任务。这是从数组中删除最高和最低分数的基本计算。每次我运行它，我得到0作为答案。我假设问题是主要的或计算得分。我很感激任何愿意花几分钟看这个的人。

#include <iostream>
using namespace std;

void printHeader(int judges);
void enterData (float scores[], int judges, float difficulty);
float calculateScore(float scores[], const int judges, float difficulty, int maxScore, int least);
int indexofLeast(float scores[], const int judges);
int indexofMax(float scores[], const int judges);

int main () {
    const int judges = 7;
    float scores [judges];
    float difficulty = 0;
    int maxScore = indexofMax(scores, judges);
    int least = indexofLeast(scores, judges);
    float finalscore = calculateScore(scores, judges, difficulty, maxScore, least);

    printHeader (judges);
    enterData (scores, judges, difficulty);  // get user input
    indexofLeast(scores, judges); // find lowest score 
    indexofMax(scores, judges); // find highest score
    calculateScore (scores, judges, difficulty, maxScore, least); // get final score
    cout << "The final score is " << finalscore << '\n';

    return 0;
}

void printHeader(const int judges) {
    cout << "This program calculates a divers score over" << judges << "judges" << endl;
}

void enterData(float scores[], const int judges, float difficulty) {
    for (int i = 0; i < judges; i++){
        cout <<"Enter score for judge " << i+1 << endl; 
        cin >> scores[i];
    }
    cout << "Enter difficulty: "<< endl;
    cin >> difficulty;
}

float calculateScore(float scores[], const int judges, float difficulty, int maxScore, int least) {
    float sum = 0;
        for (int i = 0; i < judges; i++) {
        sum += scores[i];
    }
    return (sum - scores[least] - scores[maxScore]) * difficulty * 0.6;
}

int indexofLeast(float scores[], const int judges) {
    int least = 0;
    for (int i = 1; i< judges; i++) {
        if (scores[i] < scores[least])
            least = i;
    }
    return least;
}

int indexofMax(float scores[], const int judges) {
    int maxScore = 0;
    for (int i = 1; i< judges; i++) {
        if (scores[i] > scores[maxScore]) 
            maxScore = i; 
        }
    return  maxScore;
}

对于预期输入，我输入了7个分数（0到10之间）：1,2,2,4,5,8,10 所以下降最高和最低1和10.所以sum = 21 难度在1.2和4.0之间：3.0 因此预期输入/输出为21 * 3.0 * 0.6 = 37.8 我实际上得到-0

Answer 1

因为您将难度设置为零：

    float difficulty = 0;

然后在你发现的功能中

 void enterData(float scores[], const int judges, float difficulty)

这意味着你可以通过价值得到它。所以价值不会改变，你保持零。

你需要通过参考难度：

 void enterData(float scores[], const int judges, float &difficulty)

Answer 2

您需要将difficulty作为参考传递给enterData。

void enterData(float scores[], const int judges, float &difficulty)
                                                       ^

问题是您希望它包含用户输入的值。您将其初始化为零，然后调用enterData。但是当该函数返回时，该值仍为零，因为该参数是局部变量。之后，您将结果乘以difficulty，因此结果始终为零。

使用引用返回用户输入的值应该可以解决您的问题。从语法上讲，您需要更改的唯一内容是将&添加到函数定义中，如我所示。你仍然以同样的方式调用该函数。

我恳请您发展自己批判性地分析和测试代码的技能，而不是询问人。如果您认为问题出在分数计算中，您可以轻松显示进入分数计算的所有值，并从那里向后工作... 即“为什么难度为零？在什么时候它变为零？“

要在评论中解决您的问题，您的代码会以错误的顺序执行操作。您需要在用户输入数据后分配返回值：

const int judges = 7; float scores [judges]; float difficulty = 0; printHeader (judges); enterData (scores, judges, difficulty); // get user input int maxScore = indexofMax(scores, judges); int least = indexofLeast(scores, judges); float finalscore = calculateScore(scores, judges, difficulty, maxScore, least);

Answer 3

你乘以难度从未改变为0.如果你想改变难度，将enterData的原型和定义改为以下

void enterData(float scores[], const int judges, float &difficulty)

有关通过引用传递的更详细说明，请参阅http://www.learncpp.com/cpp-tutorial/73-passing-arguments-by-reference/。

Answer 4

为了扩展之前的答案，我认为你已经陷入了一个常见的错误，即理解'='在C / C ++中是如何工作的，通常是从变量的思考中得到的，就像代数一样。

int maxScore = indexofMax(scores, judges);

这并没有描述“maxScore”是什么或将来是什么，它为它赋值。考虑 #include

int f(int n);  // some mathematical function.

int main(int argc, const char** argv)
{
   int a = 1;
   int b = f(a);
   a = 15;
   std::cout << "b = " << b << std::endl;
   return 0;
}

int f(int n) { return n * 2; } // f(n) = 2f

此程序将打印“2”，而不是“30”。

int b = f(a);
// is equivalent to
int b;
b = f(a);

在这两种情况下，b都根据当时f（a）的评估分配了一个值。更改“a”超出此点无效。

c ++从数组计算数据的问题

4 个答案: