View Compilation Error

0_0_31867553_3878.c: In function 'main':
0_0_31867553_3878.c:6:39: error: lvalue required as left operand of assignment
 while(scanf("%lf%lf%lf%lf",&x,&y,&a,&b=EOF){
                                       ^
0_0_31867553_3878.c:6:44: error: expected ')' before '{' token
 while(scanf("%lf%lf%lf%lf",&x,&y,&a,&b=EOF){
                                            ^
0_0_31867553_3878.c:10:1: error: expected expression before '}' token
 }
 ^