Compilare: user.c: In function ‘main’: user.c:22: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:23: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:27: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:31: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c: In function ‘cmmdc’: user.c:18: warning: control reaches end of non-void function