Main.cc: In function 'int main()': Main.cc:7:28: warning: format '%lf' expects a matching 'double*' argument [-Wformat=] scanf("%lf%lf%lf",&a,&b) ^ Main.cc:9:5: error: expected ';' before 'return' return 0; ^ Main.cc:9:13: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] return 0; ^