/in/foo.c: In function 'main':
/in/foo.c:7:17: error: redeclaration of 'c' with no linkage
    7 |         float z,c;
      |                 ^
/in/foo.c:4:15: note: previous declaration of 'c' with type 'float'
    4 |     float a,b,c;
      |               ^
/in/foo.c:15:20: error: '\U0000ff08' undeclared (first use in this function)
   15 |                 x2=（-b-sqrt(m)）/(2*a);
      |                    ^~
/in/foo.c:15:20: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:15:32: error: expected ';' before '\U0000ff09'
   15 |                 x2=（-b-sqrt(m)）/(2*a);
      |                                ^~
      |                                ;
/in/foo.c:22:15: warning: statement with no effect [-Wunused-value]
   22 |         else(m<0){
      |             ~~^~~
/in/foo.c:22:18: error: expected ';' before '{' token
   22 |         else(m<0){
      |                  ^
      |                  ;
/in/foo.c:7:15: warning: unused variable 'z' [-Wunused-variable]
    7 |         float z,c;
      |               ^
/in/foo.c:6:21: warning: unused variable 'x' [-Wunused-variable]
    6 |         float x1,x2,x;
      |                     ^