Help please!!

[Aye]

Write your question here.
I have an assignment about 2D array :( and its too complicated i just need help in the first function (input) and i will complete the rest..

#include<iostream>
#include<fstream>
#include<iomanip>
#include<string>

usnig namespace std;
const int max=20;
const int n=3;

int input(int [][n], string[], float&);

int main()
{
    string names[max];
    int marks[max][N];
    int classSize;
     
    classSize=input(marks,names,avg);
    input(marks, names, avg);
    cout<<"The average mark of all students is: "<<avg<<endl;

    return 0;
}

int input(int marks[][n], string names[], float& avg)
{
    ifstream fin;
    int classSize;
    int work[max], midterm[max], final[max], sum[max];
    
    fin.open("marks.txt");
    fin>>classSize;
    
    for(int i=0; i<max; i++)
    {
       getline(fin, names[i]);
       for(int j=0; j<N; j++) 
       {
         fin>>marks[i][j];
       } 
     } 

     for(int i=0; i<max; i++)
     {
       fin>>work[i]>>midterm[i]>>final[i];
       sum[i]=work[i]+midterm[i]+final[i];
     } 
     avg=sum/n;
     return classSize;
} 

[PSYCHAMERON]

Your program is full of errors! And what you want to calculate is unclear...

inside int input(int [][n], string[], float&) function...
fin.open("marks.txt");
this statement opens a file named "marks.txt" which is previously written.
That file contains a pattern of data and all other subsequent statements operate on that data.

Here is a reworked version of your wrong program, I don't know if this is what you want-

#include<iostream>
#include<fstream>
#include<iomanip>
#include<string>
#include<cstdlib>
using namespace std;

const int MAX=20;
const int n=3;
float avg;

int input(int [][n], string[], float&);

int main()
{
    string names[MAX];
    int marks[MAX][n];
    int classSize;

    classSize=input(marks,names,avg);

    input(marks, names, avg);
    cout<<"The average mark of all students is: "<<avg<<endl;

    return 0;
}

int input(int marks[][n], string names[], float& avg)
{
    ifstream fin;
    int classSize;
    int work[MAX], midterm[MAX], final[MAX], sum[MAX];

    fin.open("marks.txt");

    if(!fin) // exit the program if file is unavailable
    {
        cout << "File does not exist.\n";
        exit(1);
    }

    fin>>classSize;

    for(int i=0; i<MAX; i++)
    {
       getline(fin, names[i]);
       for(int j=0; j<n; j++)
       {
         fin>>marks[i][j];
       }
     }

     for(int i=0; i<MAX; i++)
     {
       fin>>work[i]>>midterm[i]>>final[i];
       sum[i]=work[i]+midterm[i]+final[i];
     }
     int totalSum = 0;

    for(int i = 0; i < MAX; i++) totalSum += sum[i];

     avg = (float) (totalSum/n);

     return classSize;
}

[Aye]

Thanks alot, but still facing the same problem, the average is a huge number, i did same as what you did but nothing worked..