error

[Abhas]

#include<stdio.h>
#include<conio.h>
int main()
{
    int x1,y1,x2,y2,a[2],c[2],d=1;
    gh:
    printf("insert x1,y1,x2,y2\n");
    scanf("%d\n%d\n%d\n%d\n",&x1,&y1,&x2,&y2);
    a[d]=(y2-y1)/(x2-x1);
    c[d]=y1-a[d]*x1;
    printf("y=%dx+%d\n",a[d],c[d]);
    d++;
    if(d<=2)
    {
     goto gh;
    }
    else
    {
     if (a[1]==a[2])
     {
                   printf("they are parallel");
     }
    }
    getch();
}

this is a program for finding if 2 lines are parallel
when user enters the co-ordinates of 2 points on the line
it is working well
but when the user is supposed to enter 4 datas only it asks for a fifth data which seems to have no effect on the program. but why is this happening????
plz help!!!!!!!!!

pst: i am using dev c++

[CommonTater]

    printf("insert x1,y1,x2,y2\n");
    scanf("%d\n%d\n%d\n%d\n",&x1,&y1,&x2,&y2);

You should not use \n in your formatting string... If you want separation between numbers simply add spaces or comas. It might even be better to split it in two and ask separately for each line.

    printf("insert x1,y1,x2,y2\n");
    scanf("%d,%d,%d,%d",&x1,&y1,&x2,&y2);

OR....

    printf("insert x1 y1 x2 y2\n");
    scanf("%d %d %d %d",&x1,&y1,&x2,&y2);

[Abhas]

cool! that worked!
@tater:thx. but what if i want it to b shown in new line and at the same time accept the values in one command??? is it possible??

[Salem]

> scanf("%d\n%d\n%d\n%d\n",&x1,&y1,&x2,&y2);
Any trailing matching characters after the last conversion causes scanf to keep looking until something fails the last match.

Edit:
typically, you use fgets() to read a whole line, then use sscanf() to parse it.

[Abhas]

now 1 more question: why is void main() not accepted in dev c++ though i include the c header files??

[laserlight]

now 1 more question: why is void main() not accepted in dev c++ though i include the c header files?

for what you are dealing with, the return type of main is supposed to be int.

[Abhas]

why??? it is accepted in c.

[laserlight]

why??? it is accepted in c.

There are a few details about whether it is or is not standard C that I do not wish to discuss here, but take my word for it: your information is incorrect, it is not accepted in C.