C: 用 malloc 扩展数组 [英] C: Expanding an array with malloc

问题描述

总的来说，我对 malloc 和 C 有点陌生.如果需要，我想知道如何使用 malloc 扩展其他固定大小的数组的大小.

I'm a bit new to malloc and C in general. I wanted to know how I can, if needed, extend the size of an otherwise fixed-size array with malloc.

示例:

#define SIZE 1000
struct mystruct
{
  int a;
  int b;
  char c;
};
mystruct myarray[ SIZE ];
int myarrayMaxSize = SIZE;
....
if ( i > myarrayMaxSize )
{
   // malloc another SIZE (1000) elements
   myarrayMaxSize += SIZE;
}

• 上面的例子应该清楚我想要完成什么.

(顺便说一句:我写的解释器需要这个:使用固定数量的变量，如果需要更多变量，只需动态分配它们)

(By the way: I need this for an interpreter I write: Work with a fixed amount of variables and in case more are needed, just allocate them dynamically)

推荐答案

使用 realloc，但你必须先用 malloc 分配数组.在上面的例子中，你是在堆栈上分配它.

Use realloc, but you have to allocate the array with malloc first. You're allocating it on the stack in the above example.

   size_t myarray_size = 1000;
   mystruct* myarray = malloc(myarray_size * sizeof(mystruct));

   myarray_size += 1000;
   mystruct* myrealloced_array = realloc(myarray, myarray_size * sizeof(mystruct));
   if (myrealloced_array) {
     myarray = myrealloced_array;
   } else {
     // deal with realloc failing because memory could not be allocated.
   }

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