/in/foo.c: In function 'build':
/in/foo.c:8:9: warning: implicit declaration of function 'weihu' [-Wimplicit-function-declaration]
         weihu(i,nn);
         ^~~~~
/in/foo.c: At top level:
/in/foo.c:11:6: warning: conflicting types for 'weihu'
 void weihu(int j,int nn)
      ^~~~~
/in/foo.c:8:9: note: previous implicit declaration of 'weihu' was here
         weihu(i,nn);
         ^~~~~