if else if语句C ++的问题

Question

I am working on a grade book project that has 5 students that I want to read the names in for and then with an inner loop grab 4 grades for each student. Something is not working on this loop. This what I am getting:

Please enter the name for student 1: Dave
Please enter the grade number 1 for Dave: 100
Please enter the grade number 2 for Dave: 100
Please enter the grade number 3 for Dave: 100
Please enter the grade number 4 for Dave: 10
Please enter the name for student 2: James
Please enter the grade number 5 for James: 100
Please enter the name for student 3: Sam
Please enter the grade number 5 for Sam: 100
Please enter the name for student 4: Jack
Please enter the grade number 5 for Jack: 100
Please enter the name for student 5: Mike
Please enter the grade number 5 for Mike: 100

It should grab 4 grades before it jumps to the next student. I have not been able to figure this out for the last couple hours. Here is the code I have so far:

#include <iostream>
#include <string>

using namespace std;

const int STUDENTS = 5; //holds how many students we have
const int SCORES = 4;

void getNames(string names[], double student1[SCORES], double student2[SCORES],
          double student3[SCORES], double student4[SCORES], double student5[SCORES],            int SCORES, int STUDENTS);

int main()
{
    string names[STUDENTS]  = {""};
    char grades[STUDENTS]   = {""};
    double student1[SCORES] = {0};
    double student2[SCORES] = {0};
    double student3[SCORES] = {0};
    double student4[SCORES] = {0};
    double student5[SCORES] = {0};

getNames(names, student1, student2, student3, student4, student5, SCORES,  STUDENTS);


//  Make sure we place the end message on a new line
    cout << endl;

//  The following is system dependent.  It will only work on Windows
    system("PAUSE");

    return 0;
}

void getNames(string names[], double student1[SCORES], double student2[SCORES],
          double student3[SCORES], double student4[SCORES], double student5[SCORES],     int SCORES, int STUDENTS)
{
     for (int i = 0; i < STUDENTS; i++)
     {
         cout << "Please enter the name for student " << i+1 << ": ";
         cin >> names[i];
         cout << endl;

         if (i == 0)
         {
            int count1 = 0;
            for (count1; count1 < SCORES; count1++)
            {
                cout << "Please enter the grade number " << count1+1 << " for " << names[i] <<": ";
                cin >> student1[count1];
                cout << endl;
            }
         }
         else if (i == 1)
         {
            int count2 = 0; 
            for (count2; count2 < SCORES; count2++);
            {
                cout << "Please enter the grade number " << count2+1 << " for " << names[i] <<": ";
                cin >> student2[count2];
                cout << endl;
            }
         }
         else if (i == 2)
         {
            int count3 = 0; 
            for (count3; count3 < SCORES; count3++);
            {
                cout << "Please enter the grade number " << count3+1 << " for " << names[i] <<": ";
                cin >> student3[count3];
                cout << endl;
            }
         }
         else if (i == 3)
         {
            int count4 = 0; 
            for (count4; count4 < SCORES; count4++);
            {
                cout << "Please enter the grade number " << count4+1 << " for " << names[i] <<": ";
                cin >> student4[count4];
                cout << endl;
            }
         }
         else
         {
            int count5 = 0; 
            for (count5; count5 < SCORES; count5++);
            {
                cout << "Please enter the grade number " << count5+1 << " for " << names[i] <<": ";
                cin >> student5[count5];
                cout << endl;
            }
         }

     }
}

Thanks for any help on this!

Answer 1

There's some pretty rough stuff going on in here, but the problem is that you have a semi-colon on all your inner loops except the first one:

for (count2; count2 < SCORES; count2++);

Remove the semi-colon, and the stuff in the braces will become part of the loop.

I'm going to suggest you make your code a little tidier and less error-prone by chucking all those function arguments into their own array when you enter the function, like this:

double *scores[5] = { student1, student2, student3, student4, student5 };

Then you take OUT all that repetition - the copy/paste is what caused your problems to begin with:

for (int i = 0; i < STUDENTS; i++)
{
    cout << "Please enter the name for student " << i+1 << ": ";
    cin >> names[i];
    cout << endl;

    for (int s = 0; s < SCORES; s++)
    {
        cout << "Please enter the grade number " << s+1 << " for " << names[i] <<": ";
        cin >> scores[i][s];
        cout << endl;
    }
}

Answer 2

Why can't you use two nested loops like

  for (int studix=0, stduix<STUDENTS; studix++) { 
     //...
     for (int gradix=0; gradix<SCORE; gradix++) {
        //...
     }
     //....
  }

BTW, the condition could be a more complex one, eg with the internal loop being

     bool goodgrade=true;
     for (int gradix=0; goodgrade && gradix<SCORE; gradix++) {
       // you could modify goodgrade or use break; inside the loop
     }

Don't forget the possible use of continue and break inside a loop.

And please, take time to read some good C++ programming book

Answer 3

Building on Basile's answer and my comments:

int main()
{
string names[STUDENTS]  = {""};
char grades[STUDENTS]   = {""};
double student1[SCORES] = {0};
double student2[SCORES] = {0};
double student3[SCORES] = {0};
double student4[SCORES] = {0};
double student5[SCORES] = {0};

double *gradeArray[STUDENTS];
gradeArray[0] = student1;
gradeArray[1] = student2;
gradeArray[2] = student3;
gradeArray[3] = student4;
gradeArray[4] = student5;

for (int studix=0, stduix<STUDENTS; studix++) { 
 // get the name of the student
 for (int gradix=0; gradix<SCORE; gradix++) {
    // put the grades in gradeArray[studix][gradix]...

 }
 //....
}

Yes, I know about 2 D arrays, but I am trying to make explicit how this can be done with "five individual arrays". Clumsy, but I believe this works.