我有一个带有 Movie 对象数组的 MovieController 对象。我有一个在 Controller 上调用“doAddMovie”的 MovieView 对象。
当我在 MovieController 的构造函数中调用“doAddMovie”时,一部电影被添加到数组中。但是,当我从 MovieView 调用“doAddMovie”时,出现了段错误。
谁能告诉我我做错了什么?
电影 Controller .h
#ifndef MOVIECONTROLLER_H
#define MOVIECONTROLLER_H
#include "MovieView.h"
#include "Movie.h"
class MovieView;
class MovieController
{
public:
MovieController();
void doAddMovie(string title, int year, string genre);
private:
MovieView* movieView;
Movie** movies;
};
电影 Controller .cc:
const int MAX_MOVIES = 10;
MovieController::MovieController() {
movies = new Movie*[MAX_MOVIES];
doAddMovie("Star Wars", 1977, "SciFi"); // <<-- this works
}
/* when I call this method from my MovieView object, I get a segmentation fault, pretty
* sure the fault happened on line: movies[i] = new Movie(title, year, genre);
*/
void MovieController::doAddMovie(string title, int year, string genre) {
cout << "doAddMovie; title=" << title << "; year=" << year << "; genre =" << genre;
int i = 0;
while (i < MAX_MOVIES) {
if (movies[i] == NULL) {
movies[i] = new Movie(title, year, genre); <<-- segmentation fault here
break;
}
i = i+1;
}
return;
}
最佳答案
doAddMovie()
期望在可用槽上找到一个 NULL
指针,但是在分配数组后您没有将数组槽初始化为 NULL,因此数组的内容将是随机垃圾。 doAddMovies()
在构造函数中调用时起作用的事实是侥幸。
试试这个:
class MovieController
{
public:
MovieController();
~MovieController();
void doAddMovie(string title, int year, string genre);
private:
MovieView* movieView;
Movie** movies;
};
MovieController.cc:
const int MAX_MOVIES = 10;
MovieController::MovieController()
{
movies = new Movie*[MAX_MOVIES];
memset(movies, 0, sizeof(Movie*)*MAX_MOVIES); // <-- add this
doAddMovie("Star Wars", 1977, "SciFi");
}
MovieController::~MovieController()
{
for (int i = 0; i < MAX_MOVIES; ++i)
delete movies[i];
delete[] movies;
}
void MovieController::doAddMovie(string title, int year, string genre)
{
for (int i = 0; i < MAX_MOVIES; ++i)
{
if (movies[i] == NULL)
{
movies[i] = new Movie(title, year, genre);
cout << "Movie added: title=" << title << "; year=" << year << "; genre =" << genre;
return;
}
}
cout << "Movie ignored: title=" << title << "; year=" << year << "; genre =" << genre;
}
话虽如此,您应该拥抱 C++ 内存管理并且根本不使用原始数组:
#include <vector>
class MovieController
{
public:
MovieController();
void doAddMovie(string title, int year, string genre);
private:
MovieView* movieView;
std::vector<Movie> movies;
};
MovieController.cc:
MovieController::MovieController()
{
doAddMovie("Star Wars", 1977, "SciFi");
}
void MovieController::doAddMovie(string title, int year, string genre)
{
movies.push_back(Movie(title, year, genre));
cout << "Movie added: title=" << title << "; year=" << year << "; genre =" << genre;
}
最后,如果在那之后您仍然遇到 SEGFAULT,请确保您的 MovieView
对象正在使用有效的 MovieController
调用 doAddMovie()
> 开头的对象指针。
关于c++ - 为什么我不能将新对象添加到我的对象指针数组中?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/21471810/