Compilare: user.cpp: In function ‘bool findintrie(std::string)’: user.cpp:52:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<s.size() && a->t[s[i]-97]!=NULL;i++) a=a->t[s[i]-97]; ^ user.cpp:53:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i>=s.size()) return true; else ^ user.cpp: In function ‘int main()’: user.cpp:64:28: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sub.in","r",stdin); ^ user.cpp:65:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sub.out","w",stdout); ^ user.cpp:66:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&n1); ^ user.cpp:67:26: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] root=new lista; gets(s+1); n=strlen(s+1); ^ user.cpp:72:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s+1); n=strlen(s+1); ^ /tmp/cczBkZHS.o: In function `main': user.cpp:(.text.startup+0x93): warning: the `gets' function is dangerous and should not be used.