Question

我在初始化（构造）对象的数组指针时遇到一些问题。请参阅下面的课程。类测试具有2个变量成员，一个将是数组的指针（值）及其大小（大小）；以及带有参数的构造函数和析构函数。在main函数中，我将创建对象的数组指针，但对此有问题。如果我创建一个像这样的对象：

test obj(4);将创建一个对象，其实例的value数组为4。

然后，如果我想创建对象数组：

test *obj;
obj = new test[2]{4,7};

我将创建2个对象：obj[0]大4，obj[1]大7。

因此，如果我想创建更多对象：

test *obj;
obj=new test[100]{/*here I must write 100 numbers*/}

这就是问题所在。因为我不能写这样的东西：

test *obj;
obj=new int[100]{4}

我希望每个value []（测试类的实例）大4，而我不会写100倍“ 4”。我认为类比声明数组：如果我写int array[5]={0,0,0,0,0}，则必须写4次“ 0”，否则我也可以写： int array[5]={0}，每个值都设置为0。（同样，如果写入int array[5]={5}，则第一个索引将是5，其他索引将是0）。

我应该使用默认构造函数吗？我该怎么办？

#include <iostream>

using namespace std;

class test
{
private:
int* value;
int size;

public:
test(int size)
{
    this->size = size;
    value = new int[size];
}

~test()
{
    delete[]value;
}
};

Answer 1

您可以遍历指针以初始化每个元素

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不过，最好使用test *obj = new test[100]; for(size_t i = 0; i != 100; ++i) { obj[i] = test(/*parameters*/); /* Remember to provide a move assignment operator which invalidates the pointer member, otherwise when the temporary variable is destroyed the new object pointer member will point to data no more available*/ } // ... delete [] obj;

std::vector

使用std::vector<test> obj(100, test(/*parameters*/));将std::vector对象初始化为传递其参数100次，使用指针分配（test）将默认构造每个元素，然后您将分配每个元素新值，这就是new test[100]是解决您问题的更好解决方案的原因

Answer 2

您可以在堆栈上分配内存，而无需进行动态分配和内存管理。

test array[100];
std::fill(std::begin(array), std::end(array), test(100));

请注意，您将需要一个默认的构造函数。

如何初始化数组指针对象

2 个答案: