初始化指向堆栈上指针的指针

Question

I'm a C newbie, and I'm trying to do the pointer/memory thing right...

In my case, I'm using strtol and I need to pass a **char to hold one of several return values, but allocating heap space is way overkill. The cleanest correct (I hope) way I can find, of getting space on the stack for this, is:

char *_ = NULL;
char **endptr = &_;
ret = strtol("not a number", endptr, 0);

I'm curious, is there a more succinct or idiomatic way to get this effect? I feel dirty naming things I will never use...

EDIT: to clarify, I DO intend to use endptr, just not _

Answer 1

strtol accepts NULL as the second argument. See http://www.cplusplus.com/reference/cstdlib/strtol/

So you can write your code like this:

ret = strtol("not a number", NULL, 0);

If it didn't accept NULL, you can avoid one line of code like this:

char *unused;
ret = strtol("not a number", &unused, 0);

Answer 2

If you don't need endptr, you are allowed to pass a null pointer to strtol. Otherwise I wouldn't worry about naming a variable you won't use. Although I don't think I'd name it _ as you have.