ç初始化结构中的数组 [英] C initialize array within structure

问题描述

我想有一个包含结构中的变长数组，但我有麻烦了正确的初始化。

I want to have an variable-length array contained within a structure, but am having trouble initializing it correctly.

struct Grid {
  int rows;
  int cols;
  int grid[];
}

int main() {
  struct Grid testgrid = {1, 3, {4, 5, 6}};
}

一切我试图给我的'错误：灵活数组成员的非静态初始化。误差

Everything I try gives me an 'error: non-static initialization of a flexible array member' error.

推荐答案

您可以通过使结构为静态或全局使海湾合作委员会的工作，但事实证明，该初始化灵活数组成员是不合格，所以它很可能只是用gcc到不行。这里是一个办法做到这一点，仅仅使用C99符合要求的功能...

You can make that work in gcc by making the struct either static or global, but it turns out that initializing flexible array members is non-conforming and so it is likely to not work except with gcc. Here is a way to do it that just uses C99-conforming features...

#include <stdlib.h>
#include <stdarg.h>

typedef struct Grid {
  int rows;
  int cols;
  int grid[];
} *Grid;

Grid newGrid(int, int, ...);

Grid newGrid(int rows, int cols, ...)
{
Grid g;
va_list ap;
int i, n = rows * cols;

  if((g = malloc(sizeof(struct Grid) + rows * cols * sizeof(int))) == NULL)
    return NULL;
  g->rows = rows;
  g->cols = cols;
  va_start(ap, cols);
  for(i = 0; i < n; ++i)
    g->grid[i] = va_arg(ap, int);
  va_end(ap);
  return g;
}
.
.
.
Grid g1, g2, g3;
g1 = newGrid(1, 1, 123);
g2 = newGrid(2, 3, 1, 1, 1,
                   2, 2, 2);
g3 = newGrid(4, 5, 1,  2,  3,  4,  5,
                   6,  7,  8,  9, 10,
                  11, 12, 13, 14, 15,
                  16, 17, 18, 19, 20);

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