[英]Can you pass a subclass as an argument to a function with a superclass parameter? C++
[英]Can you access methods from a ROOT object when you pass the object as an argument to a function in C++?
請原諒我的無知,但是我是C ++和ROOT的新手,我不確定自己在做什么錯。
我想要做的是編寫一個函數,該函數返回直方圖中n峰的bin位置。 以下是我的代碼:
#include <iostream>
#include <algorithm>
#include <iterator>
#include "TROOT.h"
#include "TCanvas.h"
#include "TH1.h"
#include "TF1.h"
using namespace std;
int *peak_counter1d(TH1F *histogram,int peak_num,int threshold = 5,int display = 0){
if(display == 1){
TCanvas *look = new TCanvas("look","look",500,400);
histogram->Draw();
}
int total_bins = histogram->GetNBinsX();
double peak_bins[peak_num];
peak_bins[0] = histogram->GetMaximumBin();
int counter = 1;
int *check_array; // to put previously found peak bins
while(counter < peak_num){
double peak = threshold;
double peak_loc = -500;
check_array = new int[counter];
for(int i=0; i<counter; i++){
check_array[i] = peak_bins[i]; // fills the array with previously found peak bins
}
for(int i=0; i<total_bins; i++){
if(peak < histogram->GetBinContent(i)){
bool exists = find(begin(check_array),end(checkarray),i); // makes sure this is a peak we haven't already found
if(!exists){
peak = histogram->GetBinContent(i);
peak_loc = i;
}
}
}
peak_bins[counter] = peak_loc;
counter ++;
}
delete[] check_array;
return peak_bins;
}
void testing(){
gROOT->Reset();
TH1F *histo = new TH1F("histo","try",100,0,10);
TF1 *f1 = new TF1("f1","exp(-x/10)*sin(x)*sin(x)",0,10);
double val;
for(int i=0; i<100; i++){
val = f1->Eval(i/10.0);
//cout << i << "\t" << i/100.0 << "\t" << val << endl;
histo->SetBinContent(i,val);
}
int *peak_bins;
peak_bins = peak_counter1d(histo,3,5,1);
for(int i=0; i<3; i++){
cout << i << "\t" << *(peak_bins+i) << endl;
}
}
當我在ROOT中執行此代碼時,得到以下信息:
root [] .x testing.cpp
Error: Can't call TH1F::GetNBinsX() in current scope testing.cpp:15:
Possible candidates are...
(in TH1F)
(in TH1)
*** Interpreter error recovered ***
我認為這是訪問函數內部的對象方法的問題,因為當我在testing()函數中調用histo-> GetNBinsX()方法時,我沒有遇到任何問題。 但是我不知道。
謝謝,如果我要執行其他災難性的可怕編碼操作,請告訴我。
已經指出,不能返回局部變量的地址,該局部變量在函數結束時將被銷毀。
您的另一個問題是關於:
histo->GetNbinsX()
不工作。 我試圖在腳本的主程序和子程序中都調用它:對於當前的ROOT版本,它對我來說非常合適。 在該問題中,您拼寫錯誤為GetNBinsX
(是的,這與駱駝案政策更加一致)。 也許...?
無論如何,我相信您一定會很高興地知道ROOT可以使用一種非常智能的一維峰搜索算法:尋找TSpectrum類 。
您的代碼存在各種問題。
最明顯的是:
int *peak_counter1d(TH1F *histogram,int peak_num,int threshold = 5,int display = 0)
{
//...
double peak_bins[peak_num];
//...
return peak_bins;
}
您正在返回一個指向局部變量的指針。 返回指向局部變量的指針是未定義的行為 。
下一個問題是這樣的:
int *check_array; // to put previously found peak bins
while(counter < peak_num)
{
//...
check_array = new int[counter];
}
delete[] check_array;
由於循環而未取消分配check_array
因此存在潛在的內存泄漏。 另一個問題是,如果該循環永遠不會執行,則您要對未初始化的變量調用delete []
。
下一個問題是這樣的:
int * peak_counter1d(...)
{
double peak_bins[peak_num];
//...
return peak_bins;
}
即使您可以安全地返回指向局部變量的指針,函數也會返回int *,但是您將返回double *
。
下一個問題是這樣的:
TCanvas *look = new TCanvas("look","look",500,400);
您正在分配look
,但是永遠不會取消分配它,甚至不會使用它。
您還可以在main
執行相同的操作:
TH1F *histo = new TH1F("histo","try",100,0,10);
TF1 *f1 = new TF1("f1","exp(-x/10)*sin(x)*sin(x)",0,10);
C ++不是Java。 您不必使用new
創建對象。
TH1F histo("histo","try",100,0,10);
TF1 f1("f1","exp(-x/10)*sin(x)*sin(x)",0,10);
除最后一個問題外,如果您訴諸使用std::vector
而不使用new[]
創建動態數組,則可以解決所有這些問題。
應用這些更改,代碼應如下所示(未編譯):
#include <iostream>
#include <algorithm>
#include <iterator>
#include <vector>
#include "TROOT.h"
#include "TCanvas.h"
#include "TH1.h"
#include "TF1.h"
using namespace std;
vector<int> peak_counter1d(TH1F *histogram,int peak_num,int threshold = 5,int display = 0)
{
if(display == 1)
{
// TCanvas *look = new TCanvas("look","look",500,400);
histogram->Draw();
}
int total_bins = histogram->GetNBinsX();
vector<int> peak_bins(peak_num);
peak_bins[0] = histogram->GetMaximumBin();
int counter = 1;
vector<int> check_array; // to put previously found peak bins
while(counter < peak_num){
double peak = threshold;
double peak_loc = -500;
check_array.resize(counter);
for(int i=0; i<counter; i++){
check_array[i] = peak_bins[i]; // fills the array with previously found peak bins
}
for(int i=0; i<total_bins; i++){
if(peak < histogram->GetBinContent(i)){
bool exists = find(begin(check_array),end(checkarray),i); // makes sure this is a peak we haven't already found
if(!exists){
peak = histogram->GetBinContent(i);
peak_loc = i;
}
}
}
peak_bins[counter] = peak_loc;
counter ++;
}
return peak_bins;
}
void testing(){
gROOT->Reset();
TH1F histo("histo","try",100,0,10);
TF1 f1("f1","exp(-x/10)*sin(x)*sin(x)",0,10);
double val;
for(int i=0; i<100; i++){
val = f1.Eval(i/10.0);
//cout << i << "\t" << i/100.0 << "\t" << val << endl;
histo.SetBinContent(i,val);
}
vector<int> peak_bins = peak_counter1d(&histo,3,5,1);
for(int i=0; i<3; i++){
cout << i << "\t" << peak_bins[i] << endl;
}
}
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