关于指针、类和构造函数的问题[重复]

Question

这是一个正在创建的基本直方图，但我的问题在 TH1F *hist=new TH1F("hist", "Histogram", 100, 0, 100); 我知道指针有助于将地址存储到对象，而构造函数有助于将值输入到类中的对象，但是这一行发生了什么？是否已创建指针并将其定义为构造函数？ “新”有什么用？

// Creating a histogram                                                                                                                                                                                            
void tut1()
// Void functions do not return values, simply prints a message so I assume our message here is the histogram, histograms display values but they are not themselves not values                                    
{
 TH1F *hist=new TH1F("hist", "Histogram", 100, 0, 100);
 // This is just a constructor                                                                                                                                                                                    
 // TH1F is a inherited class from the base class TH1                                                                                                                                                             
 //(the name of the histogram, the title of the histograms, number of bins, start of x axis, and ending paramater of x axis)                                                                                      
 // Here we are accessing TH1F  the capital F is for floats and we use this to use 1D histograms                                                                                                                  

 // To Fill the histogram we use                                                                                                                                                                                  
  hist->Fill(10);
  hist->Fill(40);

 // Add titles for the axis's                                                                                                                                                                                     

  hist->GetXaxis()-SetTitle("X Axis");
  hist->GetYaxis()-SetTitle("Y Axis");



  TCanvas *c1 = new TCanvas();
 hist->Draw();
   // Tcanvas is used to draw our plot it is the window that is used to display our image                                                                                                                         
}

Answer 1

变量hist 是一个指向TH1F 类型的指针。它被赋值给由构造函数创建的TH1F 的新实例。

我注意到您的程序中缺少的一件事是相应的 delete 语句。