Main.cc: In function 'int main()': Main.cc:9:9: error: 'z' was not declared in this scope z=z+(h*2); ^ Main.cc:11:22: error: 'z' was not declared in this scope printf("%.6lf\n",z); ^ Main.cc:6:12: warning: unused variable 'n' [-Wunused-variable] double n=100; ^