foo.cc: In function 'node* Sort(node*)':
foo.cc:62:21: warning: statement has no effect [-Wunused-value]
   62 |                 for(p; p!=NULL; prev=p, p=p->next)  // 遍历指针
      |                     ^
foo.cc: In function 'int main()':
foo.cc:83:13: warning: statement has no effect [-Wunused-value]
   83 |         for(p1;p1<a1+n1;p1++)
      |             ^~
foo.cc:85:13: warning: statement has no effect [-Wunused-value]
   85 |         for(p2;p2<a2+n2;p2++)
      |             ^~
foo.cc:87:13: warning: statement has no effect [-Wunused-value]
   87 |         for(p3;p3<a3+n3;p3++)
      |             ^~
foo.cc:89:15: warning: unused variable 'head1' [-Wunused-variable]
   89 |         node* head1=ordercreate(a1,n1); node* head2=ordercreate(a2,n2); node* head3=ordercreate(a3,n3);
      |               ^~~~~

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