Compilare: user.cpp: In function ‘int main()’: user.cpp:10:17: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] char ch,chl=NULL; ^ user.cpp:7:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("text.in","r",stdin); ^ user.cpp:8:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("text.out","w",stdout); ^