Compilare: user.c: In function ‘main’: user.c:9: warning: implicit declaration of function ‘malloc’ user.c:9: warning: incompatible implicit declaration of built-in function ‘malloc’ user.c:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:13: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:15: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result