View Compilation Error

0_0_37367548_13876.cpp: In function 'int main()':
0_0_37367548_13876.cpp:6:73: error: lvalue required as left operand of assignment
  while(scanf("%lf%lf%lf%lf%lf%lf%lf%lf",&x1,&y1,&x2,&y2,&x3,&y3,&x4,&y4)=8)
                                                                         ^
0_0_37367548_13876.cpp:8:6: error: 'x' was not declared in this scope
   if(x[3]>a[2]&&x[3]>a[1]||x[3]>a[3]&&x[3]>a[4]||y[3]>b[1]&&y[3]>b[2]||y[3]>b[3]&&y[3]>b[4]) 
      ^
0_0_37367548_13876.cpp:8:11: error: 'a' was not declared in this scope
   if(x[3]>a[2]&&x[3]>a[1]||x[3]>a[3]&&x[3]>a[4]||y[3]>b[1]&&y[3]>b[2]||y[3]>b[3]&&y[3]>b[4]) 
           ^
0_0_37367548_13876.cpp:8:50: error: 'y' was not declared in this scope
   if(x[3]>a[2]&&x[3]>a[1]||x[3]>a[3]&&x[3]>a[4]||y[3]>b[1]&&y[3]>b[2]||y[3]>b[3]&&y[3]>b[4]) 
                                                  ^
0_0_37367548_13876.cpp:8:55: error: 'b' was not declared in this scope
   if(x[3]>a[2]&&x[3]>a[1]||x[3]>a[3]&&x[3]>a[4]||y[3]>b[1]&&y[3]>b[2]||y[3]>b[3]&&y[3]>b[4]) 
                                                       ^