在Objective C中传递一个可变长度的int数组作为函数参数 [英] Passing an int array of variable length as a function parameter in Objective C

问题描述

  int testarr [3] [3] = {
 {1,1,1}，
 {1,0,1}，
 {1,1,1} 
}; 
 [self testCall：testarr]; 
  

调用这个函数：

<$ p $ （无效）testCall：（int [3] [3]）arr {

NSLog（@cell value is％u，arr [1] [1 ]）;
}

我需要数组的长度是可变的 - 什么是最好的方法声明函数？

使用空格不起作用：

  - （void）testCall：（int [] []）arr {
  

感谢您的帮助。 / p>

解决方案

我会把它写成：

   - （void）testCall：（int *）aMatrice; 
  

这样做可以避免使用多个malloc和数学来计算线性数组中的单个偏移量在二维数组中的x，y坐标是微不足道的。它还避免了int **所蕴含的多重malloc以及由语言延续的二维数组语法的局限性。

因此，如果你想要一个4x5的数组，你可以做：

  #define WIDTH 4 
 #define HEIGHT 5 
 #define INDEXOF（x，y）（ （y * WIDTH）+ x）
 
 int * myArray = malloc（sizeof（int）* 5 * ELEMS_PER_ROW）; 
  

然后，您可以线性初始化数组或使用嵌套for循环： $ b $ （int y = 0; y

  for（int x = 0; x   

您可以将它传递给像这样的方法：

  [foo testCall：myArray]; 
  

尽管您可能也想要携带宽度和高度，但更好的方法是创建一个IntMatrix

（所有代码都输入到SO中）
是一个NSObject的子类，它包含了所有指针算术和存储。

I have the following code which works fine...

int testarr[3][3] = {
  {1,1,1},
  {1,0,1},
  {1,1,1}
};   
[self testCall: testarr];

Which calls this function:

- (void)testCall: (int[3][3]) arr {

    NSLog(@"cell value is %u",arr[1][1]);
}

I need the array to be of variable length - What is the best way to declare the function?

Using blanks doesn't work:

- (void)testCall: (int[][]) arr { 

Thanks for your help.

解决方案

I would write this as:

- (void) testCall: (int *) aMatrice;

Doing so allows you to avoid multiple mallocs and the math to calculate a single offset in a linear array based on x, y coordinates in a 2D array is trivial. It also avoids the multiple mallocs implied by int** and the limitations of 2D array syntax perpetuated by the language.

So, if you wanted a 4x5 array, you might do:

#define WIDTH 4
#define HEIGHT 5
#define INDEXOF(x,y) ((y*WIDTH) + x)

int *myArray = malloc(sizeof(int) * 5 * ELEMS_PER_ROW);

You could then initialize the array linearly or with a nested for loop:

for(int x=0; x<width; x++)
    for(int y=0; y<height; y++)
        myArray[INDEXOF(x,y)] = ... some value ...;

And you would pass it to the method like:

[foo testCall: myArray];

Though you might want to also carry along the width and the height or, better yet, create a IntMatrix subclass of NSObject that wraps all of the pointer arithmetic and storage beyond a nice clean API.

(all code typed into SO)

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