Compilare: user.cpp: In function ‘int main()’: user.cpp:17:12: warning: unused variable ‘j’ [-Wunused-variable] int i,j,a,b; ^ user.cpp:19:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in,"%d",&n); ^ user.cpp:21:36: 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,&d,&c); ^