Compilare: user.cpp: In function ‘int main()’: user.cpp:11:11: warning: unused variable ‘j’ [-Wunused-variable] int n,j,i,nrprime=0; ^ user.cpp:11:13: warning: unused variable ‘i’ [-Wunused-variable] int n,j,i,nrprime=0; ^ user.cpp:12:22: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&n); ^