recursive function, might have inf loop

[Sevengraff]

I have to use a recursive function to print a ruler to the screen. it looks knida like this:

|       |       |
|   |   |   |   |
| | | | | | | | |
|||||||||||||||||

execept it will be about 65 characters long, and 7 lines deep.

here is my code:

// ruler.cpp
// ---------------------
// uses a recursive function to print a ruler to the screen

#include <iostream.h>

void subdivide( int lo, int hi, int level, char line[])
{
    if(level == '0')
        return;
    // get and mark midpoint
    int mid = (lo + hi) / 2;
    line[mid] = '|';
    // call again for left side
    subdivide(lo, mid-1, level-1, line);
    // call for right side
    subdivide(mid+1, hi, level-1, line);
    return;
    
}

int main( void )
{
    char line[66];
    int i;

    // prepair the array
    for(i=0; i<66; i++)
    {
        line[i] = ' ';
    }
    line[0] = '|';
    line[64] = '|';
    cout << line << "\n\n\n";
    for(i=0; i<7; i++)
    {
        subdivide(0, 65, i, line);
        cout << line << endl;
    }

    return 0;
} 

I dont get any errors when I compile it in VC++ 6, but when i run the exe it dies saying there is an error. when i try to use the debug thing, it says stack overflow. It all makes sense in my head, so i assume i have an infinate loop somewhere that i cant see because im a new programmer.
Can anyone help?