What is the meaning of "wild pointer" in C?
任何人都可以告诉我，在C中的野指针的含义，如何获得它，这是可用的C + +？
The standard does not define or use the term "wild". I'd be careful "correcting" other people's opinions about what it means, and I'd especially avoid quoting random non-normative internet junk to support my position.
To me, it would mean a pointer that neither refers to a legitimate object, nor is NULL. Possible sources of these types of pointer values might include uninitialized pointer objects, objects that have ceased to exist, computed pointer values, improperly aligned pointer values, accidental corruption of the pointer itself, or what it pointed to, etc.
int main(void)
{
int *p; // uninitialized and non-static; value undefined
{
int i1;
p = &i1; // valid
} // i1 no longer exists; p now invalid
p = (int*)0xABCDEF01; // very likely not the address of a real object
{
int i2;
p = (int*)(((char*)&i2) + 1); // p very likely to not be aligned for int access
}
{
char *oops = (char*)&p;
oops[0] = 'f'; oops[1] = 35; // p was clobbered
}
}
and so on, and so forth. There are all kinds of ways to get an invalid pointer value in C. My favourite has got to be the guy who tried to "save" his objects by writing their addresses to a file. Strangely, when he read back those pointer values during a different run of the program, they didn't point to his objects any more. Fancy, that.
But that's just what wild means to me. Since it's not a normative term, it means whatever the person who spoke or wrote it meant it to mean. Ask him or her.
A wild pointer in C is a pointer that has not been initialised prior to its first use. From Wikipedia:
Wild pointers are created by omitting necessary initialization prior to first use. Thus, strictly speaking, every pointer in programming languages which do not enforce initialization begins as a wild pointer.
This most often occurs due to jumping over the initialization, not by omitting it. Most compilers are able to warn about this.
eg
int f(int i)
{
char* dp; //dp is a wild pointer
...
}
It is not s standard term. It is normally used to refer to the pointers pointing to invalid memory location. int *p; *p = 0; //P is a wild pointer
Or
int *p = NULL;
{
int a;
p = &a; // as soon as 'a' goes out of scope,'p' is pointing to invalid location
}
*p = 0;
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