函数在C++中不起作用

Function isn't working in C++

本文关键字：不起作用 C++ 函数      更新时间：2023-10-16

我对下面的程序有一个问题，从第42行到第47行，
程序应该输出每个学生的平均值，但是它给出的是NaN而不是平均值。

有人能帮忙吗?

#include <iostream>
#include <iomanip>
using namespace std;
const int students = 3;
const int exams = 4;
int minimum( int [ ][ exams ], int, int );
int maximum( int [ ][ exams ], int, int );
double average( int [ ], int );
void printArray( int [ ][ exams ], int, int );
int main()
{
int studentGrades[ students ][ exams ] = { { 77, 68, 86, 73 }, { 96, 87, 89, 78 },
{ 70, 90, 86, 81 } };
cout << "The array is:t";
printArray( studentGrades, students, exams );
cout << "nnThe highest grade is "<< maximum( studentGrades,students,exams) <<endl;
cout << "The lowest grade is "<< minimum( studentGrades,students,exams) <<endl;
cout << fixed << setprecision( 2 );
for ( int person = 0; person < students; person++ )
cout << "nThe average grade for student " << person<< " is "<< average( studentGrades[ person ], exams );
return 0;
}
int minimum( int grades[][ exams ], int pupils, int tests )
{
int lowGrade = 100; // initialize to highest possible grade
for ( int i = 0; i < pupils; i++ )
for ( int j = 0; j < tests; j++ )
if ( grades[ i ][ j ] < lowGrade )
lowGrade = grades[ i ][ j ];
return lowGrade;
}
int maximum( int grades[][ exams ], int pupils, int tests )
{
int highGrade = 0; // initialize to lowest possible grade
for ( int i = 0; i < pupils; i++ )
for ( int j = 0; j < tests; j++ )
if ( grades[ i ][ j ] > highGrade )
highGrade = grades[ i ][ j ];
return highGrade;
}
double average( int setOfGrades[], int tests ) // here was a problem the output of the average is NaN
{
int total = 0;
for ( int i = 0; i < tests; i++ )
total += setOfGrades[ i ];
total=total/tests;
}
void printArray( int grades[][ exams ], int pupils, int tests )
{
cout << left << " [0]  [1]  [2]  [3]";
for ( int i = 0; i < pupils; i++ ) {
    cout << "nstudentGrades[" << i << "] ";
for ( int j = 0; j < tests; j++ )
cout << setw( 5 ) << grades[ i ][ j ];
}
}

您忘了退还您的总…

double average( int setOfGrades[], int tests ) 
{
   int total = 0;
   for ( int i = 0; i < tests; i++ )
   {
      total += setOfGrades[ i ];
    }
    total=total/tests;
   return total;
}

您忘记了return的值，最好按double计算平均值:

double average( int setOfGrades[], int tests )
{
  double total = 0; <------------------------- double
  ...
  return total; <----------------------------- return the value
}
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