/in/foo.c: In function 'InterSet':
/in/foo.c:15:6: warning: implicit declaration of function 'Search' [-Wimplicit-function-declaration]
   if(Search(b,nb,a[i])!=-1)
      ^~~~~~
/in/foo.c:15:13: error: 'b' undeclared (first use in this function)
   if(Search(b,nb,a[i])!=-1)
             ^
/in/foo.c:15:13: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:15:18: error: 'a' undeclared (first use in this function)
   if(Search(b,nb,a[i])!=-1)
                  ^
/in/foo.c:16:4: error: 'c' undeclared (first use in this function)
    c[nc++]=a[i];
    ^
/in/foo.c:17:10: warning: 'return' with a value, in function returning void
   return nc;
          ^~
/in/foo.c:10:6: note: declared here
 void InterSet(int a1[],int na,int b1[],int nb,int c1[])
      ^~~~~~~~
/in/foo.c: In function 'main':
/in/foo.c:22:2: error: 'nc' undeclared (first use in this function)
  nc=InterSet(a1,na,b1,nb,c1);
  ^~
/in/foo.c:22:14: error: 'a1' undeclared (first use in this function)
  nc=InterSet(a1,na,b1,nb,c1);
              ^~
/in/foo.c:22:17: error: 'na' undeclared (first use in this function)
  nc=InterSet(a1,na,b1,nb,c1);
                 ^~
/in/foo.c:22:20: error: 'b1' undeclared (first use in this function)
  nc=InterSet(a1,na,b1,nb,c1);
                    ^~
/in/foo.c:22:23: error: 'nb' undeclared (first use in this function)
  nc=InterSet(a1,na,b1,nb,c1);
                       ^~
/in/foo.c:22:26: error: 'c1' undeclared (first use in this function)
  nc=InterSet(a1,na,b1,nb,c1);
                          ^~