warning: Failed to call `main()` to execute the macro - c++

Question

I am trying to learn ROOT and I have a few codes that I can work with. Sometimes codes work but sometimes they don't.
{
c1 = new TCanvas("c1", "My Root Plots",600, 400);
c1->Divide(2,2);
c1->cd(1);
f=new TF1("f","[0]*exp(-0.5*((x-[1])/[2])**2)/(sqrt(2.0*TMath::Pi())*[2])",-100,100); f->SetTitle("Gaus;X axis ;Y axis");
f->SetParameter(0,0.5*sqrt(2*TMath::Pi()));
f->SetParameter(1,8);
f->SetParameter(2,5);
f->SetLineColor(3);
f->SetMarkerColor(1);
f->SetMarkerStyle(kOpenStar);
f->SetMarkerSize(5);
f->Draw();
c1->cd(2);
f1 = new TF1("f1", "[0]*x+[1]", 0,50);
f1->SetParameters(10,4);
f1->SetLineColor(5);
f1->SetTitle("ax+b;x;y");
f1->Draw();
}
This is the code I am trying to do. Code is kinda working , ''what do you mean kinda working''. I mean it's giving me a graph but as you can see in the code I wrote ( f->SetMarkerColor(1);
f->SetMarkerStyle(kOpenStar);) But markers didn't appear on the graph. Terminal doesn't giving me any errors. Is it my ROOT library missing ? I cannot upload images because I am new here.
I have a another problem. I want to share it maybe it will help solving the problem that I have.
void testRandom(Int_t nrEvents=500000000)
{
TRandom *r1=new TRandom();
TRandom2 *r2=new TRandom2();
TRandom3 *r3=new TRandom3();
TCanvas* c1=new TCanvas("c1","TRandom Number Generators", 800,600); c1->Divide(3,1);
TH1D *h1=new TH1D("h1","TRandom",500,0,1); TH1D *h2=new TH1D("h2","TRandom2",500,0,1); TH1D *h3=new TH1D("h3","TRandom3",500,0,1); TStopwatch *st=new TStopwatch();
st->Start();
for (Int_t i=0; i<nrEvents; i++) { h1->Fill(r1->Uniform(0,1)); } st->Stop(); cout << "Random: " << st->CpuTime() << endl; st->Start();
c1->cd(1); h1->SetFillColor(kRed+1); h1->SetMinimum(0); h1->Draw();
for (Int_t i=0; i<nrEvents; i++) { h2->Fill(r2->Uniform(0,1)); } st->Stop(); cout << "Random2: " << st->CpuTime() << endl; st->Start();
c1->cd(2); h2->SetFillColor(kGreen+1); h2->SetMinimum(0); h2->Draw();
for (Int_t i=0; i<nrEvents; i++) { h3->Fill(r3->Uniform(0,1)); } st->Stop(); cout << "Random3:" << st->CpuTime() << endl;
c1->cd(3);
h3->Draw(); h3->SetFillColor(kBlue+1); h3->SetMinimum(0);
}
This is a another code I am trying to run. But this code doesn't work an it's giving me this error.
warning: Failed to call main() to execute the macro.
Add this function or rename the macro. Falling back to .L.
I tried different things. I tried ,
root [1] .x main.cpp
root [1] .L main.cpp
still giving me same error.

Answer 1

f->SetMarkerColor(1); f->SetMarkerStyle(kOpenStar);) But markers
didn't appear on the graph.
Try f->Draw("PL") instead of f->Draw() to make the markers visible.
warning: Failed to call main() to execute the macro.
Rename your file, it should be called testRandom.cpp instead of main.cpp
Then, you can execute it with .x testRandom.cpp.