C++ 丑陋的三重间接：可扩展的缓冲区管理 struct

你有X和Y作为 struct parser_manager的成员:

    char  X    [32]; // buffer X
    char  Y    [32]; // buffer Y

你还提到了

I could then extend this out for some N number of motors by adding the buffers and pointers to the struct, then widening the PTR and CTR arrays.个

你打算怎么做？(通过在parser_manager struct 中添加更多的成员，如X和Y！)

最好创建具有构件X和Y的不同 struct .获取parser_manager struct 中 struct 的指针，以便您可以通过重新分配内存来扩展它.有了这一点，您可以在访问X和Y缓冲区时消除多级别的间接访问.

示范代码示例:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct {
    char X[32];
    char Y[32];
} buffers;

typedef struct {
    buffers * ptr_x_y;
    int numele;   // to keep track of number of elements
} parser_manager;

int main (void)
{
    parser_manager mgr = {NULL, 0};

    mgr.numele = 1;
    mgr.ptr_x_y = malloc (sizeof (buffers) * mgr.numele);
    if (!mgr.ptr_x_y) {
        exit (EXIT_FAILURE);
    }

    strcpy (mgr.ptr_x_y[0].X, "DUMMY_X1");
    strcpy (mgr.ptr_x_y[0].Y, "DUMMY_Y1");
    printf ("%s, %s\n", mgr.ptr_x_y[0].X, mgr.ptr_x_y[0].Y);
    
    mgr.numele = 2;
    buffers * temp;
    mgr.ptr_x_y = realloc (temp = mgr.ptr_x_y, mgr.numele * sizeof (buffers));
    if (!mgr.ptr_x_y) {
        free (temp);
        exit (EXIT_FAILURE);
    }

    strcpy (mgr.ptr_x_y[1].X, "DUMMY_X2");
    strcpy (mgr.ptr_x_y[1].Y, "DUMMY_Y2");
    printf ("%s, %s\n", mgr.ptr_x_y[0].X, mgr.ptr_x_y[0].Y);
    printf ("%s, %s\n", mgr.ptr_x_y[1].X, mgr.ptr_x_y[1].Y);
    
    // free dynamically allocted memory
    
    return 0;
}

输出:

DUMMY_X1, DUMMY_Y1
DUMMY_X1, DUMMY_Y1
DUMMY_X2, DUMMY_Y2

iX和iY是缓冲区X和Y的迭代器，因此你可以让它们也成为buffers struct 的成员.

如果出于某种原因，您不能使用动态内存分配函数malloc或realloc，则可以执行以下操作:

#include <stdio.h>

#define MAX_BUFFERS 10

typedef struct {
    char X[32];
    char Y[32];
} buffers;

typedef struct {
    buffers * ptr_x_y[MAX_BUFFERS];
    int numele;   // to keep track of number of elements
} parser_manager;

int main (void)
{
    parser_manager mgr = {{NULL}, 0};
    
    buffers buf1 = {.X = "DUMMY_X1", .Y = "DUMMY_Y1"};
    
    mgr.numele = 1;
    mgr.ptr_x_y[0] = &buf1;
    
    printf ("%s, %s\n", mgr.ptr_x_y[0]->X, mgr.ptr_x_y[0]->Y);    

    buffers buf2 = {.X = "DUMMY_X2", .Y = "DUMMY_Y2"};
    
    mgr.numele = 2;
    mgr.ptr_x_y[1] = &buf2;
    
    printf ("%s, %s\n", mgr.ptr_x_y[1]->X, mgr.ptr_x_y[1]->Y);
   
    return 0;
}

输出:

DUMMY_X1, DUMMY_Y1
DUMMY_X2, DUMMY_Y2