How do I compile this? GCC complains: CFLAGS="-g -pipe" make -k donut cc -g -pipe donut.c -o donut donut.c:1:2: warning: data definition has n

How do I compile this? GCC complains: CFLAGS="-g -pipe" make -k donut cc -g -pipe donut.c -o donut donut.c:1:2: warning: data definition has no type or storage class [enabled by default] donut.c: In function ‘main’: donut.c:4:16: warning: incompatible implicit declaration of built-in function ‘printf’ [enabled by default] donut.c:5:12: warning: incompatible implicit declaration of built-in function ‘memset’ [enabled by default] donut.c:9:63: error: ‘s’ undeclared (first use in this function) donut.c:9:63: note: each undeclared identifier is reported only once for each function it appears in donut.c:10:18: error: expected ‘,’ or ‘;’ before ‘in’ donut.c:11:32: error: ‘t’ undeclared (first use in this function) make: *** [donut] Errore 1 Compilation exited abnormally with code 2 at Thu Jan 23 16:11:12