了解字符串C

Question

In C, I can declare an array of strings like :

char *hey[] = {"hi", "hello", "bye"};

And then I can just iterate over it and print the elements using hey[0] and hey[1] ..

How does this work? Why don't I need to do *hey[0] to deference it??

Answer 1

因为*hey[0]将给您字符串hey[0]的第一个字符

Answer 2

If you want to dereference hey[0] , you do indeed need to use *hey[0] to dereference it. The thing is that you're not dereferencing it.

In C, saying "a string" is usually the same as saying "a pointer to some characters with a 0 at the end." So a char* is a string already. There's nothing to dereference.

(This is not entirely correct, but it's close enough)

Again, you could dereference it if you wanted to. *hey[0] would be 'h'.

Answer 3

*hey[0] is de-referencing twice.

As people have explained a string is essentially a pointer to the start of an array of characters, usually terminating in a null character '\\0' .

An array is also essentially just a pointer to the start of a list of elements.

Maybe this will help explain:

char *hey[] = {"hi", "yellow", "bye"};
char **pPointer = hey;
char one, two, three;

one = *(*pPointer+1);
two = **(pPointer+1);
three = *(pPointer[1]);

You will notice that I can just replace hey with pPointer , which is just a char** rather than a char* array. A pointer to a series of pointers (a pointer to an array).

one = 'i' - I am de-referencing pPointer once, getting to the first string "hi" then +1 takes me one element along to the character 'i' .

two = 'y' - pPointer+1 takes me to the next element in the 'string' array, to the pointer to the string "yellow", de-referencing this would give me the string "yellow" then de-referencing that gives me the character 'y' . In your case, doing pPoin

three = 'y' - This is just to show that *(pPointer+1) is the same as pPointer[1] .

This is fairly basic, however can be a bit confusing at first, I suggest you play around with pointers, arrays and strings until you feel comfortable with these concepts.

Answer 4

Because the C programming language doesn't have a native string type, what you have is a pointer to an array of character arrays (which are all '\\0', aka null, terminated). Your example of *hey[0] is perfectly valid, and actually points to the letter 'h' in "hi".