Compilare: user.cpp: In function ‘int main()’: user.cpp:13:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<strlen(s); i++) ^ user.cpp:24:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<strlen(s); i++) ^ user.cpp:10:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dir.in","r",stdin); ^ user.cpp:11:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dir.out","w",stdout); ^ user.cpp:12:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s",s); ^