(programming) A variable whose value cannot be changed directly.
Used in a Sentence
const
Definitions, parts of speech, synonyms, and sentence examples for const.
Editorial note
So maybe the problem is people declaring parameters as T & or T *, when they meant const T & or const T *?
Examples17
Definitions3
Parts of speech2
Quick take
(programming) A variable whose value cannot be changed directly.
Meaning at a glance
The clearest senses and uses of const gathered in one view.
(programming, of a variable) Whose value cannot be changed directly.
(programming, of a function) Which cannot change the value of its class’s attributes.
Definitions
Core meanings and parts of speech for const.
noun
(programming) A variable whose value cannot be changed directly.
adjective
(programming, of a variable) Whose value cannot be changed directly.
adjective
(programming, of a function) Which cannot change the value of its class’s attributes.
Example sentences
So maybe the problem is people declaring parameters as T & or T *, when they meant const T & or const T *?
Compare that to: Iterator find(T& value) const; This function signature accepts only non-const references (unless T is const).
Because what you're describing sounds like it's going to be a hot mess, const or no const.
The function takes const T & or const T *, because it doesn't change that argument.
If you're writing a library, the API should avoid including container details in function parameters, and const and non-const T should be allowed.
A non-const argument will be implicitly cast to const by the compiler.
So you can have T * (variable RAM address), T * const (fixed RAM address), const T * (variable ROM/RAM address), and const T * const (fixed ROM/RAM address).
The most common usage of const in library code is for function parameters: Iterator find(T const& value) const; The const actually _helps_ callers: find accepts both const and non-const references.
You passed what's supposedly a const object into a function that expected to be able to change it.
> but in C-family languages, 'const' modifies type, making objects that benefit from the compiler hints 'const' implies type-incompatible with objects that do not.
So, say you have a class with a const member, and you have to pass it in to a function?
But the underlying problem sounds like: you have a const object, and you want to pass it into a function.
Quote examples
As I recall isn't there also "const T const &"?
The equivalent in C++ would be: SomeClass * const foo = &instanceOfSomeClass; Here, the pointer "foo" could not change, but operations changing foo would be allowed.
Whenever I need to return a non-const reference/pointer to some inner data (which is not often) I name the method "mutableFoo()" to make clear what you're getting.
(String literals are const char *.) void blah(vector<const char * > &xs) { xs.push_back("blah"); } And you have the code calling it: vector<char * > xs; blah(xs); And that would not be valid.
Proper noun examples
Suppose we represented Add instead as: case class Add(exprs: NonEmptyList[Expr with NotAdd]) extends Expr case class Const(value: Int) extends Expr with NotAdd case class...
Frequently asked questions
Short answers drawn from the clearest meanings and examples for this word.
How do you use const in a sentence?
So maybe the problem is people declaring parameters as T & or T *, when they meant const T & or const T *?
What does const mean?
(programming) A variable whose value cannot be changed directly.
What part of speech is const?
const is commonly used as noun, adjective.