Compilare: user.cpp: In function ‘void build()’: user.cpp:45:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < ord.size(); i++) { ^ user.cpp: In function ‘int main()’: user.cpp:79:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ahocorasick.in", "r", stdin); ^ user.cpp:80:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ahocorasick.out", "w", stdout); ^ user.cpp:82:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ user.cpp:83:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &n); ^ user.cpp:85:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(a); ^ /tmp/cce2bD6f.o: In function `main': user.cpp:(.text.startup+0x59): warning: the `gets' function is dangerous and should not be used.