prog.c: In function ‘menu_principal’:
prog.c:10:23: error: implicit declaration of function ‘exit’ [-Werror=implicit-function-declaration]
if (escolha == 0) exit(0);
^~~~
prog.c:10:23: error: incompatible implicit declaration of built-in function ‘exit’ [-Werror]
prog.c:10:23: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’
prog.c:3:1:
+#include <stdlib.h>
prog.c:10:23:
if (escolha == 0) exit(0);
^~~~
cc1: all warnings being treated as errors