如何将double [] []传递给方法调用？ [英] How to pass double[][] into a method call?

问题描述

您好我正在尝试使用double filter [3] [3]格式初始化一个具有double值的对象;
但是我一直收到以下错误。

Hi I am trying to init an object with a double value in the format double filter[3][3]; but i keep getting the following error.

在分配时无法将'double [3] [3]'转换为'double'。

cannot convert 'double[3][3]' to 'double' in assignment.

在我的标题中我有这个

@interface filter : NSObject
{
    double **matrix;
}
@property(nonatomic)double **matrix;
-(id)initWithMatrix:(double**)filterMatrix;

我的课程内有这种方法。

inside my class i have this method.

-(id)initWithMatrix:(double**)filterMatrix
{
    matrix = filterMatrix;
    return self;
}

我试图这样称呼它。

double filter[3][3] = {0,0,0,0,1,0,0,0,0};
MyMatrix *myMatrix = [[MyMatrix alloc] initWithMatrix:filter];

我现在收到错误。

Error: Cannot convert double[*][3] to double** in argument passing

这个问题的任何帮助都会很棒。
谢谢
A

Any help on this issue would be amazing. Thanks A

推荐答案

二维数组与指针指向不同-a指针。您有两种选择 - 更改过滤器类以包含2D数组，或更改初始化以使用指针指针。

A two-dimensional array is not the same thing as a pointer-to-a-pointer. You have two choices - change the filter class to contain a 2D array, or change your initialization to use pointer-to-pointers.

在＃1选项中，您可以在过滤器实例中保留数组的副本，而不是只是拿着一个指针。您需要更改类接口：

In choice #1, you're could keep a copy of the array in your filter instance, instead of just holding a pointer. You need to change the class interface:

@interface filter : NSObject
{
    double matrix[3][3];
}

-(id)initWithMatrix:(double[3][3])filterMatrix;

然后你的 initWithMatrix：的实现可以只是做一个 memcpy（）或相当于将数据复制到你的实例。

Then your implementation of initWithMatrix: can just do a memcpy() or the equivalent to copy the data into your instance.

选择＃2有点不同。保持其他代码不变，但更改初始化过滤器：

Choice #2 is a bit different. Keep your other code the way it is, but change your initialization of filter:

double row0[3] = {0,0,0};
double row1[3] = {0,1,0};
double row2[3] = {0,0,0};
double **filter[3] = { row0, row1, row2 };

它可能更安全 malloc（）全部那些数组，因为否则你最终会在过滤器类中引用堆栈变量，但我想你明白了。

It's probably safer to malloc() all of those arrays, since otherwise you're going to end up with references to stack variables in your filter class, but I think you get the idea.

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