测试指针是否指向已分配的内存 [英] Test if pointer points to allocated memory
问题描述
无论如何测试指针是否指向已分配的内存或
不是吗？
例如，如果我有一个指针，如char * p，那么是否有标准
方法测试以下作业是否已经应用了
？
p =（char *）malloc（sizeof（char）* n）;
Is there anyway to test if a pointer points to allocated memory or
not?
For example if I have a pointer such as char *p is there a standard
way to test whether an assignment such as the following has been
applied?
p = (char *) malloc(sizeof(char) * n);
推荐答案
Andrew< an *********** @ ca.com>潦草地写了下面的内容：
Andrew <an***********@ca.com> scribbled the following:
无论如何都要测试一个指针是指向分配的内存还是
不是？
例如，如果我有一个指针，如char * p，那么标准
测试是否已应用如下任务的方法？
p =（char *）malloc（sizeof（char）* n）;
Is there anyway to test if a pointer points to allocated memory or
not?
For example if I have a pointer such as char *p is there a standard
way to test whether an assignment such as the following has been
applied?
p = (char *) malloc(sizeof(char) * n);
不便携。
-
/ - Joona Palaste（pa*****@cc.helsinki .fi）-------------芬兰-------- \
\-- http://www.helsinki.fi/~palaste ---------------- -----规则！ -------- /
在狗的外面，一本书是男人最好的朋友。无论如何，在狗的内心，它太黑了
。
- Groucho Marx
Not portably.
--
/-- Joona Palaste (pa*****@cc.helsinki.fi) ------------- Finland --------\
\-- http://www.helsinki.fi/~palaste --------------------- rules! --------/
"Outside of a dog, a book is a man''s best friend. Inside a dog, it''s too dark
to read anyway."
- Groucho Marx
安德鲁写道：
无论如何测试指针是否指向已分配的内存或
不是吗？
例如，如果我有一个指针，如char * p是否有一种标准的方法来测试是否已经应用了以下任务？
p =（char *）malloc（sizeof（char）* n）;
Is there anyway to test if a pointer points to allocated memory or
not?
For example if I have a pointer such as char *p is there a standard
way to test whether an assignment such as the following has been
applied?
p = (char *) malloc(sizeof(char) * n);
如果指针未初始化或已被释放
而未被重新分配，则无法评估指针。
如果您知道指针值为NULL或
指向内存，则可以检查是否为NULL。
我认为你可以只需添加另一个对象来保持
跟踪该行是否已执行。
int applied = 0;
p =（char *）malloc（sizeof（char）* n）;
applied = 1;
我也是su你对malloc的
返回值有疑问，但我不确定。
完成malloc任务后，
你总是需要检查NULL。
p = malloc（n * sizeof * p）;
if（p == NULL）{
/ *聪明地处理它* /
}
-
pete
If a pointer is uninitialized or has been freed
without being reassigned, then you can''t evaluate the pointer.
If you know that a pointer value is either NULL or
points to memory, you can check for NULL.
I think you could just add another object to keep
track of if that line was executed.
int applied = 0;
p = (char *) malloc(sizeof(char) * n);
applied = 1;
I also suspect that you have a question about the
return value of malloc, but I''m not sure.
After a malloc assignment has been made,
you always need to check for NULL.
p = malloc(n * sizeof *p);
if (p == NULL) {
/* deal with it intelligently */
}
--
pete
Andrew写道：
无论如何测试指针是指向已分配的内存还是
不是？
例如，如果我有一个像char * p这样的指针，是否有一种标准的方法可以测试是否已经应用了以下任务？
p =（char *）malloc（sizeof（char）* n）;
Is there anyway to test if a pointer points to allocated memory or
not?
For example if I have a pointer such as char *p is there a standard
way to test whether an assignment such as the following has been
applied?
p = (char *) malloc(sizeof(char) * n);
不要施放malloc。这是不必要的，并且隐藏了错误。
出于所有实际目的，你的答案是否定的。但是，如果你
执行free（p）;并且程序会变为BOOM你可以相当
确保p没有被malloced，或者已经被释放了。我很有信心
这对你来说是一个很大的帮助和安慰。
-
Chuck F（cb * *******@yahoo.com）（cb********@worldnet.att.net）
可用于咨询/临时嵌入式和系统。
< http://cbfalconer.home.att.net>使用worldnet地址！
Don''t cast malloc. It is unnecessary and hides errors.
To all practical purposes, your answer is no. However if you
execute "free(p);" and the program goes BOOM you can be fairly
sure that p was not malloced, or has already been freed. I''m sure
this is a great help and comfort to you.
--
Chuck F (cb********@yahoo.com) (cb********@worldnet.att.net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home.att.net> USE worldnet address!
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