如何在运行时收缩结构矩阵（例如，使用 realloc（））

问：

如何在运行时收缩结构（例如，使用 reallocate（））matrix

我有一个矩阵，我用它来设置一个大小为 3 的向量，其中包含条目 （，，）。如何缩小向量的大小以保留前 2 个元素并删除第三个元素 （）？我尝试使用但没有成功struct1233realloc()

最后，我希望得到以下输出：

1 2 3
1 2

代码如下：

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

typedef struct {
  size_t nrows, ncols;
  size_t *array;
} Matrix ;

int ncol = 3;
int nrow = 1;

void print_matrix(Matrix * matrix);

int main()
{
  Matrix *mat1 = (Matrix *) malloc(sizeof(Matrix));
  mat1->nrows = nrow;
  mat1->ncols = ncol;
  mat1->array = (size_t *) malloc(mat1->nrows * mat1->ncols * sizeof(int));
  mat1->array[0 * ncol + 0] = 1;
  mat1->array[0 * ncol + 1] = 2;
  mat1->array[0 * ncol + 2] = 3;
  print_matrix(mat1);
  mat1->nrows = mat1->nrows - 1;
  mat1->array = (size_t *) realloc(mat1, nrow * ncol * sizeof(int));
  print_matrix(mat1);
  free(mat1);
}

void print_matrix(Matrix * matrix)
{
  for (size_t row =0; row<matrix->nrows; row++)
  {
    for (size_t col =0; col<matrix->ncols; col++)
    {
      printf("%zu ", matrix->array[row * ncol + col]);
    }
    printf("\n");
  }
}

编辑多亏了答案，这里是工作代码：

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

typedef struct {
  size_t nrows, ncols;
  size_t *array;
} Matrix ;

int ncol = 3;
int nrow = 1;

void print_matrix(Matrix * matrix);

int main()
{
  Matrix *mat1 = (Matrix *) malloc(sizeof(Matrix));
  mat1->nrows = nrow;
  mat1->ncols = ncol;
  mat1->array = (size_t *) malloc(mat1->nrows * mat1->ncols * sizeof(*mat1->array));
  if (mat1 == NULL)
  {
    printf("Could not allocate memory\n");
    exit(EXIT_FAILURE);
  }
  else
  {
    mat1->nrows = nrow;
    mat1->ncols = ncol;
    mat1->array = (size_t *) malloc(mat1->nrows * mat1->ncols * sizeof(*mat1->array));
    mat1->array[0 * ncol + 0] = 1;
    mat1->array[0 * ncol + 1] = 2;
    mat1->array[0 * ncol + 2] = 3;
    print_matrix(mat1);
    mat1->ncols = mat1->ncols - 1;
    mat1->array = (size_t *) realloc(mat1->array, mat1->nrows * mat1->ncols * sizeof(*mat1->array));
    if (mat1 == NULL)
    {
      printf("Could not allocate memory\n");
      exit(EXIT_FAILURE);
    }
    print_matrix(mat1);
    free(mat1);
  }
}

void print_matrix(Matrix * matrix)
{
  for (size_t row =0; row<matrix->nrows; row++)
  {
    for (size_t col =0; col<matrix->ncols; col++)
    {
      printf("%zu ", matrix->array[row * ncol + col]);
    }
    printf("\n");
  }
}