/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,x2==(-b-n)2*a;
      |  ~~^~~~~~~~
/in/foo.c:9:12: error: expected ';' before numeric constant
    9 |  x1==(-b+n)2*a,x2==(-b-n)2*a;
      |            ^
      |            ;
/in/foo.c:10:11: warning: format '%f' expects argument of type 'double', but argument 2 has type 'char *' [-Wformat=]
   10 |  printf("%f","%f",x1,x2);
      |          ~^  ~~~~
      |           |  |
      |           |  char *
      |           double
      |          %s
/in/foo.c:10:9: warning: too many arguments for format [-Wformat-extra-args]
   10 |  printf("%f","%f",x1,x2);
      |         ^~~~