View Compilation Error

0_0_16152473_14743.c: In function 'cmp':
0_0_16152473_14743.c:11:15: error: 'cases' undeclared (first use in this function)
     return (*(cases *)a).t-(*(cases *)b).t;
               ^
0_0_16152473_14743.c:11:15: note: each undeclared identifier is reported only once for each function it appears in
0_0_16152473_14743.c:11:22: error: expected expression before ')' token
     return (*(cases *)a).t-(*(cases *)b).t;
                      ^
0_0_16152473_14743.c:11:38: error: expected expression before ')' token
     return (*(cases *)a).t-(*(cases *)b).t;
                                      ^
0_0_16152473_14743.c: In function 'main':
0_0_16152473_14743.c:28:28: error: 'cases' undeclared (first use in this function)
         qsort(ted,n,sizeof(cases),cmp);
                            ^