/in/foo.c: In function 'main':
/in/foo.c:6:10: warning: format '%f' expects argument of type 'float *', but argument 2 has type 'double' [-Wformat=]
    6 |  scanf("%f""%f""%f",a,b,c);
      |         ~^          ~
      |          |          |
      |          float *    double
/in/foo.c:6:8: warning: format '%f' expects argument of type 'float *', but argument 3 has type 'double' [-Wformat=]
    6 |  scanf("%f""%f""%f",a,b,c);
      |        ^~~~           ~
      |                       |
      |                       double
/in/foo.c:6:14: note: format string is defined here
    6 |  scanf("%f""%f""%f",a,b,c);
      |             ~^
      |              |
      |              float *
/in/foo.c:6:8: warning: format '%f' expects argument of type 'float *', but argument 4 has type 'double' [-Wformat=]
    6 |  scanf("%f""%f""%f",a,b,c);
      |        ^~~~             ~
      |                         |
      |                         double
/in/foo.c:6:18: note: format string is defined here
    6 |  scanf("%f""%f""%f",a,b,c);
      |                 ~^
      |                  |
      |                  float *
/in/foo.c:7:5: warning: statement with no effect [-Wunused-value]
    7 |  n*n==b*b-4*a*c;
      |  ~~~^~~~~~~~~~~
/in/foo.c:9:4: warning: statement with no effect [-Wunused-value]
    9 |  x1==(-b+n)/(2*a)；
      |  ~~^~~~~~~~~~~~~~
/in/foo.c:9:18: error: expected ';' before '\U0000ff1b'
    9 |  x1==(-b+n)/(2*a)；
      |                  ^~
      |                  ;
/in/foo.c:12:1: error: expected declaration or statement at end of input
   12 | }
      | ^
/in/foo.c:5:11: warning: unused variable 'x2' [-Wunused-variable]
    5 |  float x1,x2,a,b,c,n;
      |           ^~