Question

这就是我所拥有的。我在代码中注意到我在底部遇到了麻烦。我正在尝试查找用户输入的成绩的总平均值。用户在底部附近放了四个不同的等级。它们的权重为10％。

程序为30％，练习为10％。期末考试为30％。请告诉我该怎么做的建议。不要告诉我代码。我想在寻求额外帮助之前尝试自己编写代码，以便我了解这一点。我只是想知道下一步要采取的步骤。谢谢。

#include <iostream>
#include <string>
#include <vector>
#include <numeric>
using namespace std;

float average(const vector<float> &values);

int main()
{
    cout << "Kaitlin Stevers" << endl;
    cout << "Program 11" << endl;
    cout << "December 8th 2016" << endl;
    cout << endl;
    cout << endl;

    vector<float> exerciseGradesVector;
    float exerciseGrades;

    cout << "Enter the grades for the Exercises. Type 1000 when you are finished." << endl;
    while ( std::cin >> exerciseGrades && exerciseGrades != 1000 )
    {
        exerciseGradesVector.push_back (exerciseGrades);
    }
    cout << endl;

    cout << "You entered " << exerciseGradesVector.size() << " grades." << endl;
    cout << endl;
    cout << "The Exercise grades you entered are : ";
    for(int i=0; i < exerciseGradesVector.size(); i++)
    {
        cout << exerciseGradesVector[i] << "  ";
    }
    cout << endl;
    float averageExerciseGrades = average( exerciseGradesVector );
    cout << "The average of the Exercise grades is: " << averageExerciseGrades << endl;
    cout << endl;   

    vector<float> programGradesVector;
    float programGrades;
    cout << "Enter the grades for the Programss. Type 1000 when you are finished." << endl;
    while ( std::cin >> programGrades && programGrades != 1000 )
    {
        programGradesVector.push_back (programGrades);
    }
    cout << endl;
    cout << "You entered " << programGradesVector.size() << " grades." << endl;
   cout << endl;
    cout << "The Program grades you entered are : ";
    for(int i=0; i < programGradesVector.size(); i++)
    {
        cout << programGradesVector[i] << "  ";
    }
    cout << endl;
    float averageProgramGrades = average( programGradesVector );
    cout << "The average of the Program grades is: " << averageProgramGrades << endl;
    cout << endl;

    float midTermTest;
    float midTermProgram;
    float finalExamTest;
    float finalExamProgram;

    cout << "Please enter the Midterm Exam score for the multipule choice section. " << endl;
    cin >> midTermTest;
    cout << "Please enter the Midterm Exam score for the Programming section. " << endl;
    cin >> midTermProgram;
    cout << "Please enter the Final Exam score for the multipul choice section. " << endl;
    cin >> finalExamTest;
    cout << "Please enter the Final Exam score for the Programming section. " << endl;
    cin >> finalExamProgram;
///////I need to find the average off ALL the grades.. All the 4 inputs above and the two vectors need to be in the average.
///////I am not sure if I need to read the 3 numbers before the last one into a vector because each is worth 10 percent and then do the next step or what. Would that mess it up? Advice please?  
    vector<float> allGradesVector;
    float totalaverageGrade = average( allGradesVector ); //This is obviously not finished. Just ignore it..

   }


float average( const vector<float> &values )
{
    float sum = 0.0;

    for ( size_t i = 0; i < values.size(); i++ ) sum += values[i];

    return values.size() == 0 ? sum : sum / values.size();
}

Answer 1

一个简单的for循环可以解决问题。

float total = 0;
int count = 0
for(int i = 0; i < dropOnee; i++)
{
  total+= programGradesVector[i];
  count++;
}
cout << "The average is: " total/count << endl;

我还建议使用更具描述性的名称来计算。

Answer 2

您可以使用std::accumulate

float average = accumulate(programGradesVector.begin(), programGradesVector.end(), 0.0) /  programGradesVector.size();

Answer 3

我建议您使用while来替换do while。因为你可以先输入1000。

您可以这样写：

while ( std::cin >> exerciseGrades && fabs(exerciseGrades - 1000) < 0.000001 )
{
    exerciseGradesVector.push_back (exerciseGrades);
}

我使用fabs函数来解决float在某些时候是不准确的。

关于平均值函数：

您可以使用std :: accumulate：

float average = accumulate(programGradesVector.begin(), programGradesVector.end(), 0.0) /  programGradesVector.size();

或者像你一样自己实现：

float average( const std::vector<float> &values )
{
    float sum = 0.0f;
    int nSize = values.size();

    for(int i = 0; i < nSize; ++i)
    {
        sum += values[i];
    }

    return nSize == 0 ? sum : sum / nSize;
}

如何获取输入C ++程序的平均值？

3 个答案: