c program for Sutherland Hodgemen Polygon clipping

#include<stdio.h>
#include<conio.h>
#include<graphics.h>
#include<math.h>
#include<dos.h>
void dda(int,int,int,int,int,int,int,int);
void dda(int x1,int y1,int x2,int y2,int xmin,int ymin,int xmax,int ymax)
{
float dx,dy;
float steps,x=x1,y=y1;
int i=0;
dx=x2-x1;
dy=y2-y1;
if(abs(dx)>=abs(dy))
steps=abs(dx);
else
steps=abs(dy);
dx=dx/steps;
dy=dy/steps;
while(i++<=steps)
{
if(x>=xmin && x<=xmax && y>=ymin && y<=ymax)
{
line(x,y,x2,y2);
getch();
return;
}
x=x+dx;
y=y+dy;
}
}

void main()
{
int n,gd,gm,x1,x2,y1,y2,xRec,yRec,b1,b2,b3,b4,l,b,yMin,yMax,xMin,xMax;
float m;
int a[10][4],i,j, flag=0,in=0;
gd=DETECT;
initgraph(&gd,&gm,"C:\\TC\\BGI");
printf("Enter the length and breadth of the clipping window:\n");
scanf("%d%d",&l,&b);
printf("Enter the starting co-ord of the rectangle\n");
scanf("%d%d",&xRec,&yRec);
cleardevice();
rectangle(xRec,yRec,xRec+l,yRec+b);
getch();
cleardevice();
printf("Enter the no of lines\n");
scanf("%d",&n);
for(i=0;i<n;i++)
{
printf("Enter the co-ord of line %d\n",i+1);
for(j=0;j<2;j++)
{
scanf("%d",&a[i][j]);
}
a[i][2]=a[0][0];
a[i][3]=a[0][1];
if(i!=0)
{
a[i-1][2]=a[i][0];
a[i-1][3]=a[i][1];
}
}
cleardevice();
rectangle(xRec,yRec,xRec+l,yRec+b);
for(i=0;i<n;i++)
{
line(a[i][0],a[i][1],a[i][2],a[i][3]);
}
getch();
cleardevice();
rectangle(xRec,yRec,xRec+l,yRec+b);
xMin=xRec;
yMin=yRec;
xMax=xRec+l;
yMax=yRec+b;
for(i=0;i<n;i++)
{
flag=0;
x1=a[i][0];
x2=a[i][2];
y1=a[i][1];
y2=a[i][3];
if(x1>=xMin && x1<=xMax && y1>=yMin && y1<=yMax)
flag++;
if(x2>=xMin && x2<=xMax && y2>=yMin && y2<=yMax)
flag++;
switch(flag)
{
case 0: break;
case 1:
if(x2>=xMin && x2<=xMax && y2>=yMin && y2<=yMax)
{
dda(x1,y1,x2,y2,xMin,yMin,xMax,yMax);
}
else
{
dda(x2,y2,x1,y1,xMin,yMin,xMax,yMax);
}
break;
case 2:
line(x1,y1,x2,y2);
break;
}
}
getch();
closegraph();
}