Two-Dimensional Char Array

[illlojik]

Hello, I am having a problem writing this program. I'm supposed to make a two-dimensional array of characters to hold the five student names.

Like so:

const int NUM_STUDENTS = 10;
const int STRING_SIZE = 10;
char names[NUM_STUDENTS][STRING_SIZE];

But the user is supposed to enter the names, which is what I am having trouble doing. Can anyone please explain to me how to go about doing so? Thanks

[mzimmers]

Are you asking how to input data into the array?

	for (int i = 0; i < NUM_STUDENTS; i++)
	{
		cout << "enter student name: ";
		cin >> names [i];
	}

[illlojik]

Just like that? What about the STRING_SIZE part? I don't need to do anything with it?

[mzimmers]

Oh, I suppose it would be a good idea to make sure the read doesn't overrun your array.

istream& get ( char* s, streamsize n );
istream& get ( char* s, streamsize n, char delim );

Either of these should work for you.

[illlojik]

I don't know if I'm just confusing myself or what... This is the problem that I am supposed to do:

Write a program that uses a two-dimensional array of characters to hold the five stu-
dent names, a single-dimensional array of five characters to hold the five student's let-
ter grades, and five single-dimensional arrays of four doubles to hold each student's
set of test scores.

The program I wrote sort of worked but since it's always good to get the input of others, I want to make sure I am understanding everything clearly. So, I'll do a sample model for the problem above:

const int NUM_STUDENTS = 5,   //number of students
              STRING_SIZE = 10;     //maximum size of each string
              GRADES = 4;               //number of test scores for each student
char names[NUM_STUDENTS][STRING_SIZE];  //The names of five students with maximum 
                                        //of 10 characters for each name entered
char letter_grade[NUM_STUDENTS];         //the letter grades for the five students
double test1[GRADES],            //
            test2[GRADES],           //
            test3[GRADES],           //     the test grades for the five students. not sure if this 
            test4[GRADES],           //     part is correct.
            test5[GRADES];          // 

[illlojik]

would this be right so far?

[mzimmers]

It looks OK, except that 10 characters isn't much space to hold a name. You might want to bump that up; memory's cheap these days.

And, while your test1/2/3/4/5 arrays will work, they're poorly named. I'd call them "student1grades, etc. or something like that.

Apart from these minor issues, this looks like you can make it work.

[andywestken]

why not

double test_grades[NUM_STUDENTS][GRADES];

to parallel what you're doing with names and letters_grades?

Oops -- didn't read back up the thread far enough -- Sorry!

[mzimmers]

That's not what the instructions call for.

[illlojik]

Because it asked for five single-dimensional arrays of four doubles to hold each student's
set of test scores.

[illlojik]

Then the second part of the instruction is:

The program should allow the user to enter each student's name and his or her four
test scores. It should then calculate and display each student's average test score and a 
letter grade based on the average.

The only part that is giving me trouble is entering the student's names. Would I use a nested for loop or something?

for(int count = 0; count < NUM_STUEDNTS; count++)
{
      for(int row = 0; row < STRING_SIZE; row++)
      {
            cin >> names[count][row];    //something like this??
      }
}

Or would it be something like:

cin.getline(names, STRING_SIZE);

[mzimmers]

Actually, somewhere in between. Using getline is probably the right approach, but you need to dereference names once (not twice). And a single for loop should work fine.

[illlojik]

This seems to work just fine :)

for(int count = 0; count < NUM_STUDENTS; count++)
	{
		cout << "\n Student " << (count + 1) << ":  ";
		cin.getline(names[count], STRING_SIZE);
	}

[mzimmers]

Bingo. You're making good progress. Let us know if you need any more help.