centru.cpp: In constructor 'instream::instream(const char*)': centru.cpp:47: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result centru.cpp: In constructor 'instream::instream(const char*)': centru.cpp:47: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result centru.cpp: In constructor 'instream::instream(const char*)': centru.cpp:47: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result centru.cpp: In member function 'void instream::advance()': centru.cpp:69: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result centru.cpp: In function 'int main()': centru.cpp:92: warning: unused variable 'dif'