this is from a text book and i dont know why it isnt compiling? #include <iostre

Question

this is from a text book and i dont know why it isnt compiling?

#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>

using namespace std;

bool isPeak(const double grid [][N], int r, int c);

int main()
{
   int const N = 25;
   int nrows, ncols;
   double elevation [N][N];
   string filename;
   ifstream filel;

   cout << "Enter the name of the input file. ";
   cin >> filename;
   filel.open(filename.c_str());
   if(filel.fail())
   {
       cerr << "Error opening input file ";
       exit(1);
   }
   filel >> nrows >> ncols;
   if(nrows > N || ncols > N)
   {
       cerr << "Grid is too large, adjust program.";
       exit(1);
   }
   for (int i=0; i<nrows-1; ++i)
   {
       for (int j=0; j<ncols; ++j)
       {
           filel >> elevation[i][j];
       }
   }
   cout << "Top left point defined as row 0, column 0 ";
   for (int i=1; i<nrow-1, ++i)
   {
       for (int j=1; j<ncols-1; ++j)
       {
           if(isPeak(elevation, i, j))
           {
               cout << "Peak at row: " << i
               << " column: " << j << endl;
           }
       }
   }
   filel.close();
   return 0;
}
   bool isPeak(const double grid[][N], int i, int j)
{
   if ((grid[i-1][j]<grid[i][j]) &&
   (grid[i+1][j]<grid[i][j]) &&
   (grid[i][j-1]<grid[i][j]) &&
   (grid[i][j+1]<grid[i][j]))
   return true;
   else
   return false;
}

Explanation / Answer

Hi,

There were a few mistakes which I have corrected. Please find the correct code below:

CODE:

#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
using namespace std;
bool isPeak(const double grid [][25], int r, int c);
int main()
{
int const N = 25;
int nrows, ncols;
double elevation [N][N];
string filename;
ifstream filel;
cout << "Enter the name of the input file. ";
cin >> filename;
filel.open(filename.c_str());
if(filel.fail())
{
cerr << "Error opening input file ";
exit(1);
}
filel >> nrows >> ncols;
if(nrows > N || ncols > N)
{
cerr << "Grid is too large, adjust program.";
exit(1);
}
for (int i=0; i<nrows-1; ++i)
{
for (int j=0; j<ncols; ++j)
{
filel >> elevation[i][j];
}
}
cout << "Top left point defined as row 0, column 0 ";
for (int i=1; i<nrows-1; ++i)
{
for (int j=1; j<ncols-1; ++j)
{
if(isPeak(elevation, i, j))
{
cout << "Peak at row: " << i
<< " column: " << j << endl;
}
}
}
filel.close();
return 0;
}
bool isPeak(const double grid[][25], int i, int j)
{
if ((grid[i-1][j]<grid[i][j]) &&
(grid[i+1][j]<grid[i][j]) &&
(grid[i][j-1]<grid[i][j]) &&
(grid[i][j+1]<grid[i][j]))
return true;
else
return false;
}

Errors :

1.You have to declare the array with a size. and

2.nrows variable was declared but it was used as nrow. the alphabet 's' was missing.

Hope it helped. Do rate:)

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