Thread Breakpoint at an array assignment

im trying to make an array that is (n x n) large depending on what value you enter, and then populate that array with random integers. Could you guys please help me with two problems?

  1. Any values of n greater than 4 give "error at display" in the last rows, if i display what value it would have been if it wasn't an error it is the same across, and something huge like 20019238394
  2. Why does it create the same number all the way across? Is it not generating new random numbers?

    #include <iostream> #include <string> #include <cmath> #include <cstdlib> #include <time.h> using namespace std; int arrayCreate(int); int main(int argc, const char * argv[]) { int n; cout << "enter how big your array is (n) , it will be shown as (n x n)" << endl; cin >> n; cout << "------------------------------" << endl; arrayCreate(n); return 0; } int arrayCreate(int n){ srand (time(NULL)); int y=0, x=0; int original[x][y]; //putting in random values for (int y=0; y< n; y++){ for (int x=0; x< n; x++){ int check = (rand() % 9 + 1); if (check < 10) original[x][y] = check; else cout << "error"; } } //displaying those values for (y=0; y<n; y++){ for (x=0; x<n; x++){ if (original[x][y] < 10) cout << original[x][y] << " "; else cout << "error at display"; } cout << " y is " << y << endl;} return original[x][y]; }

-------------Problems Reply------------

You're declaring your array with size [0][0]. What you wanted was size [n][n].

As a result, you're writing to unallocated memory. To correct:

int original[n][n];

should work for you.

when creating a new array you should allocate it on the heap, so it would be:

int** original = new int* [n]; // creates column
for(int i=0; i<n; i++)
original[i] = new int [n]; // creates rows

then when it's no longer needed, have to free memory

for(int i=0; i<n; i++)
delete original[i];

delete original;

Category:c# Views:3 Time:2018-08-05
Tags: arrays random

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