Compilare: user.c: In function 'prefix': user.c:14: warning: suggest parentheses around assignment used as truth value user.c: In function 'main': user.c:27: warning: implicit declaration of function 'strlen' user.c:27: warning: incompatible implicit declaration of built-in function 'strlen' user.c:48: warning: format '%i' expects type 'int', but argument 2 has type 'long int' user.c:50: warning: format '%i' expects type 'int', but argument 2 has type 'long int' /tmp/cco9M44k.o: In function `main': user.c:(.text+0xd9): warning: the `gets' function is dangerous and should not be used.