Compilare: user.cpp: In function ‘int main()’: user.cpp:45:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dictree.in","r",stdin); ^ user.cpp:46:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dictree.out","w",stdout); ^ user.cpp:47:15: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:48:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] if (n>0) scanf("\n"); ^ user.cpp:50:28: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] for (i=1;i<=n;i++){ gets(s); s1[i]=s; } ^ /tmp/ccvoPFvP.o: In function `main': user.cpp:(.text.startup+0xba): warning: the `gets' function is dangerous and should not be used.