/in/foo.c: In function 'search':
/in/foo.c:5:13: error: 'n' undeclared (first use in this function)
 for(i=0;i<y;n++)
             ^
/in/foo.c:5:13: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c: In function 'main':
/in/foo.c:16:1: warning: implicit declaration of function 'output' [-Wimplicit-function-declaration]
 output(a,y);
 ^~~~~~
/in/foo.c: In function 'search':
/in/foo.c:7:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^