Compilare: user.c: In function ‘read_data’: user.c:70: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:73: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:76: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:80: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:82: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c: In function ‘main’: user.c:116: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:117: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result