playlist.cpp: In function 'int verif()': playlist.cpp:23: warning: unused variable 'j' playlist.cpp:23: warning: unused variable 'a' playlist.cpp:23: warning: unused variable 'b' playlist.cpp:23: warning: unused variable 'c' playlist.cpp:23: warning: unused variable 'ok' playlist.cpp: In function 'int main()': playlist.cpp:30: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result playlist.cpp:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result playlist.cpp:33: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result playlist.cpp:35: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result