Compilare: user.cpp: In function ‘int main()’: user.cpp:16:10: warning: unused variable ‘enter’ [-Wunused-variable] bool enter, ok; ^ user.cpp:16:17: warning: unused variable ‘ok’ [-Wunused-variable] bool enter, ok; ^ user.cpp:17:9: warning: unused variable ‘pr’ [-Wunused-variable] int pr, dif; ^ user.cpp:17:13: warning: unused variable ‘dif’ [-Wunused-variable] int pr, dif; ^ user.cpp:13:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("prefix.in", "rt", stdin); ^ user.cpp:14:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("prefix.out", "wt", stdout); ^ user.cpp:18:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int T; scanf("%d\n", &T); ^ user.cpp:20:20: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s + 1); n = strlen(s + 1); ^ /tmp/ccKbzZfZ.o: In function `main': user.cpp:(.text.startup+0x7e): warning: the `gets' function is dangerous and should not be used.