Compilare: user.cpp: In function ‘bool operator<(const drum&, const drum&)’: user.cpp:30:10: warning: statement has no effect [-Wunused-value] a.per>b.per; ^ user.cpp:31:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:85:38: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in,"%d%d%d%d",&n,&m,&d,&p); ^ user.cpp:91:46: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in,"%d%d%d%d",&a,&b,&cat,&per); ^