Basic Turn Procedure

#include <stdio.h>
#include <unistd.h>

int main()
{
    int act_hdg;
    int sel_hdg;
    int turn;
    bool main_loop = true;

    while(main_loop == true)
    {
        printf("Input actual heading ");
        scanf("%d", &act_hdg);
        printf("Input required heading (or 999 to exit) ");
        scanf("%d", &sel_hdg);

        if(sel_hdg == 999)
            main_loop = false;

        turn = sel_hdg - act_hdg;

        if(turn > 180)
            turn = turn - 360;
        if(turn < -180)
            turn = turn + 360;

        printf("Turn is %d\n", turn);

        while(turn != 0)
        {
            if(turn > 0)
            {
                act_hdg++;
                turn--;
            }
            if(turn < 0)
            {
                act_hdg--;
                turn++;
            }
            if(act_hdg > 360)
                act_hdg -= 360;
            if(act_hdg < 1)
                act_hdg += 360;

            printf("Heading is %dº and %dº of turn remain\n", act_hdg, turn);
            usleep(250000);
        }
        printf("\n");
    }
    return 0;
}