struct in function call

[Jasper]

any idea why i get 0.0000 printed out for slength instead of my wanted value?

...
int main(void)
{
    struct Segment seg;
    double seglength();
    double slength;
     
    do
    {
        /* request 1st point coordinates */
        printf("\nEnter first point coordinates x1 y1: ");
        scanf("%d" "%d" , &seg.x1 , &seg.y1);
        /* Flush keyboard buffer */
        fflush(stdin);
        /* request 2nd point coordinates */
        printf("\nEnter second point coordinates x2 y2: ");
        scanf("%d" "%d" , &seg.x2 , &seg.y2);
        /* Flush keyboard buffer */
        fflush(stdin);
        /* Print length of segment */
       printf("Segment length:%.5f" , slength);    
    } while(OKtoContinue());
    
    return 0;
}

double seglength(struct Segment seg)
 {
  double slength;
  slength = sqrt((seg.x2 - seg.x1) * (seg.x2 - seg.x1) + (seg.y2 - seg.y1) * (seg.y2 - seg.y1));
  return slength;
 }

[BEN10]

any idea why i get 0.0000 printed out for slength instead of my wanted value?

...
int main(void)
{
    struct Segment seg;
    double seglength();
    double slength;
     
    do
    {
        /* request 1st point coordinates */
        printf("\nEnter first point coordinates x1 y1: ");
        scanf("%d" "%d" , &seg.x1 , &seg.y1);
        /* Flush keyboard buffer */
        fflush(stdin);
        /* request 2nd point coordinates */
        printf("\nEnter second point coordinates x2 y2: ");
        scanf("%d" "%d" , &seg.x2 , &seg.y2);        /* Flush keyboard buffer */
        fflush(stdin);
        /* Print length of segment */
       printf("Segment length:%.5f" , slength);    
    } while(OKtoContinue());
    
    return 0;
}

double seglength(struct Segment seg)
 {
  double slength;
  slength = sqrt((seg.x2 - seg.x1) * (seg.x2 - seg.x1) + (seg.y2 - seg.y1) * (seg.y2 - seg.y1));
  return slength;
 }

Look at your scanf calls carefully. Where are you calling seglength by the way?

[vart]

your slength variable is not initialized and not updated anywhere

fflush(stdin) is undefined - read FAQ