/in/foo.cc: In function 'void mul0(int*, int, int*)':
/in/foo.cc:49:6: warning: unused variable 'lenx' [-Wunused-variable]
  int lenx=lenint(x);
      ^~~~
/in/foo.cc: In function 'void copy(int*, int*)':
/in/foo.cc:83:19: warning: 'sizeof' on array function parameter 'a' will return size of 'int*' [-Wsizeof-array-argument]
  int lena=sizeof(a);
                   ^
/in/foo.cc:81:17: note: declared here
 void copy(int a[],int b[])
                 ^