View Compilation Error

0_0_23944821_29651.cpp: In function 'int main()':
0_0_23944821_29651.cpp:7:53: error: expected ')' before '~' token
  while (scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2)~)
                                                     ^
0_0_23944821_29651.cpp:7:54: error: expected primary-expression before ')' token
  while (scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2)~)
                                                      ^