Compilare: user.cpp: In function ‘int three()’: user.cpp:56:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] return a[v[k - 1]]; ^ user.cpp:39:9: warning: unused variable ‘result’ [-Wunused-variable] int result; ^ user.cpp: In function ‘int main()’: user.cpp:90:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] a[c] ^= 1; ^ user.cpp:61:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("bool.in", "r", stdin); ^ user.cpp:65:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("bool.out", "w", stdout); ^ user.cpp:67:13: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets (x); ^ user.cpp:83:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d\n", &n); ^ user.cpp:88:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%c", &c); ^ /tmp/ccGciwNy.o: In function `main': user.cpp:(.text.startup+0x5b): warning: the `gets' function is dangerous and should not be used.