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.
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:
Difference between char* var; and char *var;? [duplicate]
(1 answer)
Placement of the asterisk in pointer declarations
(14 answers)
Closed 5 years ago.
class str
{
char *p;
public:
string(const char *s);
}
I am confused about the difference between these two declarations.
const char * is a pointer to a const char, you cant change the value being pointed to, but you can change the pointer
char * const is a constant pointer to a char, [behaving like a reference type] you can change the value pointed to but you cant change the pointer.
const char * const is a constant pointer to a constant char, [both are constants]
This question already has answers here:
What is the difference between const int*, const int * const, and int const *?
(23 answers)
Closed 6 years ago.
I am a beginner to c++. The below code snippet is taken from a program for parsing text input.
const int MAX_CHARS_PER_LINE = 512;
const int MAX_TOKENS_PER_LINE = 20;
const char* const DELIMITER = ",";
I couldn't find a reason for why the programmer used
const pointer
for variable DELIMITER, as he didn't use const pointer for other variables. Please clarify.
512 and 20 are constants of type int. Their values can be stored in objects (variables) of type int. There's no need for pointers.
A string literal like "," is not a simple scalar value. It's of type const char[2], an array of two chars. (const means read-only.)
Though arrays and pointers are very different things (and don't let anyone tell you otherwise!), arrays in C and C++ are most commonly manipulated via pointers to their elements. Thus a char* pointer can be used to, for example, traverse a string and provide access to each of its elements.
The extra const means that the pointer itself cannot be modified.
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 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.