Compilare: user.cpp: In function ‘void back(std::string, std::string, std::string)’: user.cpp:45:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( s.length() <= lim ) ^ user.cpp:56:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( ; i < s.length(); i++) ^ user.cpp: In function ‘void citire()’: user.cpp:16:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&N); ^ user.cpp:20:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&L[ i ]); ^ user.cpp:25:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c",&c); ^ user.cpp: In function ‘int main()’: user.cpp:125:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("perle.in","r",stdin); ^ user.cpp:126:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("perle.out","w",stdout); ^