Keep getting (*** stack smashing detected ***: terminated) with a two dimensional array.

Question

This program works well for a little bit, but when I ever I try to print a number from the second column in the array student_1, it will say {*** stack smashing detected ***: terminated}> I don't know how to print out any numbers in the second column or at least exchange its value with another integer to print-out without getting this error.

/*
   Programmer:     Joshua Elias
   Program Name: Star Pattern Displayer
   Date:                  3/15/2022
   Version:             14.0. 23918.0.?
   Description: This program takes the user input for three tests for two students and
   displays the test scores and also displays the average of the test scores.
*/
#include <iostream>
#include <cmath>

using namespace std;

int average(int student_1[2][3])
//function that will be used to display the test scores and average.
{
    int sum1 = 0;
    int sum2 = 0;
    //used to help find the average more easily.
    cout<<"       Student 1 Student 2 " << endl;
    for(int i=0;i<3;++i)
    //function will display every test score for both students 1 and 2.
    {
        cout << "Test " << i + 1 << "        " << student_1[i][0];
        //display test and its number.
        cout << "        " << student_1[i][1] << endl;
        //displays the test scores
        //adds up the sum of every test for both students 1 and 2.
        sum1 = sum1 + student_1[i][0];
        sum2 = sum2+student_1[i][1];
    }
    cout << "Average Test Score of Student 1: " << sum1 / 3 << endl;
    //calculates, then displays the test average.
  return 0;
  //ends the function.
}

int main()
{
  int student_1[2][3]={{0,1,2},{3,4,5}};
  //arrays made basic so that the user can input into them.
  cout << "This program will show you the average test score of two students" << endl;
  cout << "Please input the the test scores for student 1 Test 1: ";
  cin >> student_1[0][0];
  cout << "Test 2: ";
  cin >> student_1[1][0];
  cout << "Test 3: ";
  cin >> student_1[2][0];
    cout << "Please input the the test scores for student 2 Test 1: ";
  cin >> student_1[0][1];
  cout << "Test 2: ";
  cin >> student_1[1][1];
  cout << "Test 3: ";
  cin >> student_1[2][1];
  //gets the user's input for every test score for both student 1 and 2.
  cout << endl;
  average(student_1);
  cout << "Average Test Score of Student 2: " << endl;
  cout << (student_1[0][1]+student_1[1][1]+student_1[2][1])/3;
  //calls the function that will display the test score and average.
    return 0;
}

Answer 1

The problem is that you index your array incorrectly.

You defined student_1 to be a 2 x 3 two-dimensional array. But later, when you try to index it as it would be a 3 x 2 array (e.g. student_1[2][1])

int student_1[2][3]={{0,1,2},{3,4,5}};
// ...
cout << (student_1[0][1]+student_1[1][1]+student_1[2][1])/3;

The simplest way to fix this is to define your student_1 array as a 3 x 2 matrix instead:

int student_1[2][3];

Please note that it is totally unnecessary to initialize your student_1 with values as you'll read them from the user anyway.