c - 释放 C 中分配的内存

Question

这个问题已经有答案了:

How much memory would be freed if pointer is changed in C? (3 个回答)

已关闭 7 年前。

假设我已经分配了足够大的char**数组。

为什么我可以free(arr)但不是free(arr + 5) ？

请注意，我说的不是 arr[0]或arr[5] .

Answer 1

您始终使用 malloc()、realloc() 或 calloc( 返回的指针调用 free() )。您不得传递任何其他指针。

来自free()手册:

The free() function frees the memory space pointed to by ptr, which must have been returned by a previous call to malloc(), calloc(), or realloc(). Otherwise, or if free(ptr) has already been called before, undefined behavior occurs. If ptr is NULL, no operation is performed.