Question

This is a noob question. I have an array called Counter[N][N] and I want to do something like:

While (each element of Counter < 10000) {do something}

While (there exists an element of Counter < 10000) {do something}

Is there an easy way of doing that in C?

Answer 1

This function tests whether the counter array passed in has an element smaller than the specified value:

bool has_element_less_than(int value, int counter[N][N])
{
    for (int i = 0; i < N; i++)
    {
        for (int j = 0; j < N; j++)
        {
             if (counter[i][j] < value)
                 return true;
        }
    }

    return false;
}

You use it:

if (has_element_less_than(10000, counter))
    do_something();

You could deal with variable dimension arrays in C99 by passing N as a parameter to the function. It assumes you have the C99 header <stdbool.h> available and included.

---

Is this what you’re after? You mention ‘While’ so it isn’t clear whether you need to use a while loop — if you do, I think this does the job:

int i = 0;

while (i < N)
{
    int j = 0;
    while (j < N)
    {
         if (counter[i][j] < 10000)
         {
             counter[i][j] = do_something(i, j, counter[i][j]);
         }
         j++;
    }
    i++;
}

Or, more colloquially but using for loops:

for (int i = 0; i < N; i++)
{
    for (int j = 0; j < N; j++)
    {
         if (counter[i][j] < 10000)
         {
             counter[i][j] = do_something(i, j, counter[i][j]);
         }
    }
}

Note that this code is using C99; you can declare i and j outside the loops and it becomes C89 code. Also, if for any reason you need i or j (or, more likely, both) after the loop, you need to declare the variables outside the loop.

The second solution with for loops is more idiomatic C; the for loop is very good for this job and is what you should plan to use, not least because it packages all the loop controls on a single line, unlike the while loop solution which has the initialize code on one line (outside the loop), the condition on another, and the reinitialization on yet a third line.