What is strange about the cycle?

Question

C++ / C#

#include <fstream>
using namespace std;
char a[100][100];
int i,j,m,n,r;
main()
{
    ifstream in("input.txt");
    ofstream out("output.txt");
    in>>m>>n;
    for (;i<m; i++)
        for (;j<n; j++)
        in>>a[i][j];
}

Used by MinGW. Can you explain why the loop doesn't work? "i" and "j" are zero, exactly less than "m" and "n" but the loop is not completely executed.

Answer 1

What do you mean ignored? It's just that after the first execution of the inner loop, j will remain equal to n, and therefore the inner loop will be executed only once. (it's still lucky that in C++ global variables are initialized to zero)
And all because my mother told me to declare variables as close as possible to the place of use :)