Compilare: user.c:2: warning: built-in function ‘log’ declared as non-function user.c: In function ‘read_data’: user.c:17: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:18: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:19: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:20: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:23: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c: In function ‘main’: user.c:33: warning: control reaches end of non-void function