"nick" <i1********@yahoo.com> wrote in message
news:dl***********@justice.itsc.cuhk.edu.hk...
| ex1.char q[]="Nick";
| q[0]='D';
|
| ex2.char *q ="Nick";
| q[0]='D';
|
| ex1 is correct, but ex2 occurs run time error.
|
| why?
|
| thanks!
ex1.char is not a type.
ex2.char is not a type.
Who knows, maybe ex1 and ex2 are actually types?
So which would q be, the pointer or the array?
Lets suppose...
char q[] = "Nick";
char *p = &q[0]; // its a single char
*p = 'S';
std::cout << q; // prints "Sick" (note*)
Note: lets not get confused here, a char array is not handled like
arrays of other primitive types or arrays of user-defined types when it
comes to output. You can thank compatibility for that headache. A
std::string is a much better candidate here.
std::string s("I'm a string");
std::string *p_s = &s; // pointer to an entire string, not just a char
<ah, relief>
Are ex1 and ex2 structs or classes? That would be nice to know. If
so...char is reserved.
struct ex1 {
char c;
};
ex1 q[] = {'a', 'b', 'c'}; // treat them as what they are
ex1 *p = &q[0]; // p points to the first element
ex1 *p2 = {'u'}; // error
at which point p2 is undefined, null, zipfa, dangerous, bad karma, UB
(pick one)
An unitialized pointer is nothing, in my humble opinion: its not even a
pointer. Call it a null pointer if you like. To me its a black hole. A
few will argue, and disscuss, and scream, and beg but its still a black
hole here. Adamantly so.
The closer you get to a black hole, and the more often you get anywhere
near it, it's eventually bound to suck you in.
