This question already has answers here:
What is the difference between const int*, const int * const, and int const *?
(23 answers)
Closed 8 years ago.
I was wondering what two constant signs on a function parameter does in this case?
void virtual_via_pointer( const Employee * const );
This isn't specific to function parameters.
const Employee*
Means a "mutable pointer to a constant instance of Employee".
Employee* const
Means a "constant pointer to a mutable instance of Employee".
const Employee* const
Means a "constant pointer to a constant instance of Employee".
See also the Spiral Rule.
The pointer and the pointee are both constant.
Related
This question already has answers here:
What is the difference between char * const and const char *?
(19 answers)
Closed 4 years ago.
given variable that define as char** const var; , what is defined here as const (var or *var) ?
And in the general case, how can I know it? (namely, given it: char**** const var , what is defined here as const?)
You read right-to-left. The const refers to what is to the left. The exception is that a declaration may start with const, in which case it refers to the thing on the right.
char const * const is a constant pointer to a constant char. So char ** const is a constant pointer to a pointer-to-char.
This question already has answers here:
What is the difference between const int*, const int * const, and int const *?
(23 answers)
Closed 7 years ago.
I understand that the const keyword means that you can't change a variable's value so what does it mean if it used like this :
const char* const& message
The first const stays for the pointer reference itself cannot be changed, so you cannot do something like:
message = &something;
the second const is for the content of the pointer, so you cannot do something like:
*message = something;
This question already has answers here:
What is the difference between const int*, const int * const, and int const *?
(23 answers)
constant pointer vs pointer on a constant value [duplicate]
(11 answers)
Closed 8 years ago.
For a given type T:
What is the difference between const T * and T * const?
Also, are there other places that const can go? For instance, is T const * a thing? Can you have more than one const in an expression, such as const T * const?
const T *x means x points to an object of type T, but that object should not be modified.
On the other hand, T *const x means the pointer itself cannot be modified (but the object it points to can).
const T *const x is just a combination of the two; both the pointer and the object it points to cannot be modified.
This question already has answers here:
What is the difference between const int*, const int * const, and int const *?
(23 answers)
Closed 8 years ago.
I just found some code that doesn't compiles because somewhere a type is
const char *
and somewhere else
char const *
It is customary to differentiate between these two forms and the meaning is different ?
I suppose that I could suppose in one case a pointer to a const char and in the other case an unmodifiable pointer to a char, but I am not sure of anything .
The two are completely identical and interchangeable. If the const is before the *, it refers to the pointed-to data type. If the const is after the *, it refers to the pointer itself.
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
What is the difference between const int*, const int * const, and int const *?
I am trying to understand how const works in a function parameter. What is the difference between void function(int const *&i); and void function(const int *&i);? And I would appreciate if you gave an example of their implementation and of the usage of i.
They are the same, just read it from right to left:
First example: i is a reference to a pointer of a constant integer.
Second example: i is a reference to a pointer of an integer constant.
The placement of const only changes things on either side of the pointer. For example:
const int* i
means: i is a pointer to a constant integer
whereas int* const i
means: i is a constant pointer to an integer.
Those declarations are equivalent. For more info, see this page.
Best place for const correctness is the - C++ FAQ Lite
They're both the same.
It means a reference to a pointer to a const int.