Compilare: user.cpp: In function ‘int main()’: user.cpp:81:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < strlen(t); ++i){ ^ user.cpp:67:40: 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:68:42: 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:70:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s\n%d\n",t,&q); ^ user.cpp:74:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s",ch); N = strlen(ch); ^