What's the Difference Between `ptr `, ` ptr`, ` *ptr`, and `(*ptr) ` in C ?

Pointers: ptr , ptr, and *ptr

These pointer expressions are often confusing, so let's clarify their meanings:

1. *ptr :

• Dereferences the pointer ptr and returns the value pointed to.
• Increments the pointer ptr to point to the next element.

Example:

int arr[] = {1, 2, 3};
int *ptr = arr;
cout << *ptr++; // Outputs 1 and then points to the next element (2)

2. * ptr:

• Increments the pointer ptr first, moving it to the next element.
• Then, дереференсирует the updated pointer, returning the value pointed to.

Example:

int arr[] = {1, 2, 3};
int *ptr = arr;
cout << *++ptr; // Moves the pointer to the next element and outputs 2

3. *ptr:

• Dereferences the pointer ptr, returning the value pointed to.
• Then, increments the dereferenced value.

Caution: Increments the value, not the pointer ptr.

Example:

int *ptr = new int(5); // Points to a dynamically allocated integer
cout << ++*ptr; // Outputs 6 and updates the dereferenced integer to 6

4. Bonus: (*ptr) :

• Forces dereferencing of ptr, which obtains the pointed-to value.
• Increments the dereferenced value.

Caution: Similar to *ptr, it affects the value, not the pointer itself.

Example:

int *ptr = new int(5);
cout << (*ptr)++; // Outputs 5 and updates the dereferenced integer to 6

The above is the detailed content of What's the Difference Between `ptr `, ` ptr`, ` *ptr`, and `(*ptr) ` in C ?. For more information, please follow other related articles on the PHP Chinese website!