C语言 如何释放c 2d数组
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how to free c 2d array
提问by lina
i have the following code:
我有以下代码：
int **ptr = (int **)malloc(sizeof(int*)*N);
for(int i=0;i<N;i++)
ptr[i]=(int*)malloc(sizeof(int)*N));
how can i free ptr using free? should i loop over ptr and free ptr[i]? or just do
我怎样才能免费使用 ptr free？我应该遍历 ptr 和 free ptr[i] 吗？或者只是做
free(ptr)
and ptr will be freed?
而ptr会被释放吗？
采纳答案by James Bedford
You will have to loop over ptr[i], freeing each int* that you traverse, as you first suggest. For example:
正如您首先建议的那样，您将不得不遍历 ptr[i]，释放您遍历的每个 int*。例如：
for (int i = 0; i < N; i++)
{
int* currentIntPtr = ptr[i];
free(currentIntPtr);
}
回答by Donotalo
Just the opposite of allocation:
与分配正好相反：
for(int i = 0; i < N; i++)
free(ptr[i]);
free(ptr);
回答by Rob?
Yes, you must loop over ptrand free each ptr[i]. To avoid memory leaks, the general rule is this: for each malloc(), there must be exactly one corresponding free().
是的，您必须循环ptr并释放每个ptr[i]. 为避免内存泄漏，一般规则是：对于每个malloc()，必须恰好有一个对应的free()。
回答by Srikanth
for(int i=0;i<N;i++) free(ptr[i]);
free(ptr);
you are not checking for malloc failure to allocate. You should always check.
您没有检查 malloc 分配失败。你应该经常检查。
回答by 7vujy0f0hy
Simple
简单的
while (N) free(ptr[--N]);
free(ptr);
Handsome
英俊的
#define FALSE 0
#define TRUE 1
typedef int BOOL;
void freev(void **ptr, int len, BOOL free_seg) {
if (len < 0) while (*ptr) {free(*ptr); *ptr++ = NULL;}
else while (len) {free(ptr[len]); ptr[len--] = NULL;}
if (free_seg) free(ptr);
}
freev(ptr, N, TRUE); /* if known length */
freev(ptr, -1, TRUE); /* if NULL-terminated */
freev(ptr, -1, FALSE); /* to keep array */
Patrician
贵族
GLibfunctions:
GLib函数：
g_ptr_array_free()for freeing arrays of pointers,g_strfreev()for freeing arrays of strings.
g_ptr_array_free()用于释放指针数组，g_strfreev()用于释放字符串数组。
I find it hard to do any serious C programming without GLib. It introduces things such as dynamic stringsand lays foundationsfor functional programming. It should really be part of the standard C run-time library. It would give C a breath of fresh air. It would make C a reasonable and competitive language again for the year 2019.But because it isn't, it will add 1 MB to your application (either in DLL size or in executable size). Also the Windows distribution is maintained by sadists.
我发现没有 GLib 就很难进行任何严肃的 C 编程。它介绍了诸如动态字符串之类的东西，并为函数式编程奠定了基础。它真的应该是标准 C 运行时库的一部分。它会让 C 呼吸新鲜空气。这将使 C在 2019 年再次成为一种合理且具有竞争力的语言。但由于它不是，它将为您的应用程序增加 1 MB（无论是 DLL 大小还是可执行文件大小）。此外，Windows 发行版由虐待狂维护。
