MLMessageReady()

#include "mathlink.h"

/* calculate the sum of the integers in a list and check for a message on a link */

int f(MLINK lp, int *list, int len)
{
    int sum;
    while(len--)
    {
        sum += *list++;
        if(MLMessageReady(lp))
            { /* read the message */ }
    }

    return sum;
}