Questions tagged [constants]
Constants in programming are definitions whose value is fixed throughout a program's execution. Literals in most languages are constants, for example. In referentially transparent programming styles, all definitions are constant. A const-qualified data storage area (object, field, variable, parameter) is one that "never changes", thus allowing extra code generator optimizations and additional static checking of program correctness.
constants
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What is the difference between const int*, const int * const, and int const *?
I always mess up how to use const int*, const int * const, and int const * correctly. Is there a set of rules defining what you can and cannot do?
I want to know all the do's and all don'ts in terms ...
ultraman
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What is the difference between const and readonly in C#?
What is the difference between const and readonly in C#?
When would you use one over the other?
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'Static readonly' vs. 'const'
I've read around about const and static readonly fields. We have some classes which contain only constant values. They are used for various things around in our system. So I am wondering if my ...
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How do I create a constant in Python?
How do I declare a constant in Python?
In Java, we do:
public static final String CONST_NAME = "Name";
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Are there constants in JavaScript?
Is there a way to use constants in JavaScript?
If not, what's the common practice for specifying variables that are used as constants?
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Constants in Objective-C
I'm developing a Cocoa application, and I'm using constant NSStrings as ways to store key names for my preferences.
I understand this is a good idea because it allows easy changing of keys if ...
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What's the difference between constexpr and const?
What's the difference between constexpr and const?
When can I use only one of them?
When can I use both and how should I choose one?
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PHP | define() vs. const
In PHP, you can declare constants in two ways:
With define keyword
define('FOO', 1);
Using const keyword
const FOO = 1;
What are the main differences between those two?
When and why should you use ...
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answers
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What is meant with "const" at end of function declaration? [duplicate]
I got a book, where there is written something like:
class Foo
{
public:
int Bar(int random_arg) const
{
// code
}
};
What does it mean?
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Why Is `Export Default Const` invalid?
I see that the following is fine:
const Tab = connect( mapState, mapDispatch )( Tabs );
export default Tab;
However, this is incorrect:
export default const Tab = connect( mapState, mapDispatch )( ...
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671
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16
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Declare a const array
Is it possible to write something similar to the following?
public const string[] Titles = { "German", "Spanish", "Corrects", "Wrongs" };
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"static const" vs "#define" vs "enum"
Which one is better to use among the below statements in C?
static const int var = 5;
or
#define var 5
or
enum { var = 5 };
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What is the difference between char s[] and char *s?
In C, one can use a string literal in a declaration like this:
char s[] = "hello";
or like this:
char *s = "hello";
So what is the difference? I want to know what actually happens in terms of ...
user188276
551
votes
9
answers
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C# naming convention for constants?
private const int THE_ANSWER = 42;
or
private const int theAnswer = 42;
Personally I think with modern IDEs we should go with camelCase as ALL_CAPS looks strange. What do you think?
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Does using const on function parameters have any effect? Why does it not affect the function signature?
For example, imagine a simple mutator that takes a single boolean parameter:
void SetValue(const bool b) { my_val_ = b; }
Does that const actually have any impact? Personally I opt to use it ...
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How can you define a static data member of type const std::string?
I'd like to have a private static constant for a class (in this case a shape-factory).
I'd like to have something of the sort.
class A {
private:
static const string RECTANGLE = "...
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What is the difference between the "const" and "final" keywords in Dart?
What is the difference between the const and final keywords in Dart?
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const vs constexpr on variables [duplicate]
Is there a difference between the following definitions?
const double PI = 3.141592653589793;
constexpr double PI = 3.141592653589793;
If not, which style is preferred in C++11?
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What is the difference between "const" and "val"?
I have recently read about the const keyword, and I'm so confused! I can't find any difference between const and the val keyword, I mean we can use both of them to make an immutable variable, is there ...
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votes
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PHP Constants Containing Arrays?
This failed:
define('DEFAULT_ROLES', array('guy', 'development team'));
Apparently, constants can't hold arrays. What is the best way to get around this?
define('DEFAULT_ROLES', 'guy|development ...
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6
answers
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Why can't I have "public static const string S = "stuff"; in my Class?
When trying to compile my class I get an error:
The constant 'NamespaceName.ClassName.CONST_NAME' cannot be marked static.
at the line:
public static const string CONST_NAME = "blah";
I could ...
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418
votes
20
answers
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Declaring static constants in ES6 classes?
I want to implement constants in a class, because that's where it makes sense to locate them in the code.
So far, I have been implementing the following workaround with static methods:
class MyClass ...
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Why does JSHint throw a warning if I am using const?
This is the error I get when using const:
<error line="2" column="1" severity="warning" message="'const' is available in ES6 (use esnext option) or Mozilla JS extensions (use moz)...
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answers
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Const in JavaScript: when to use it and is it necessary?
I've recently come across the const keyword in JavaScript. From what I can tell, it is used to create immutable variables, and I've tested to ensure that it cannot be redefined (in Node.js):
const x = ...
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Constants in Kotlin -- what's a recommended way to create them?
How is it recommended to create constants in Kotlin? And what's the naming convention? I've not found that in the documentation.
companion object {
//1
val MY_CONST = "something"
//2
...
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votes
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answers
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What is the best way to implement constants in Java? [closed]
I've seen examples like this:
public class MaxSeconds {
public static final int MAX_SECONDS = 25;
}
and supposed that I could have a Constants class to wrap constants in, declaring them static ...
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369
votes
19
answers
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views
What is the difference between char * const and const char *?
What's the difference between:
char * const
and
const char *
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votes
3
answers
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"sending 'const NSString *' to parameter of type 'NSString *' discards qualifiers" warning
I have Constants NSString, that I want to call like:
[newString isEqualToString:CONSTANT_STRING];
Any wrong code here?
I got this warning:
sending 'const NSString *' to parameter of type '...
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Are variables declared with let or const hoisted?
I have been playing with ES6 for a while and I noticed that while variables declared with var are hoisted as expected...
console.log(typeof name); // undefined
var name = "John";
...variables ...
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Proper use of const for defining functions
Are there any limits to what types of values can be set using const in JavaScript, and in particular, functions? Is this valid? Granted it does work, but is it considered bad practice for any reason?
...
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What does the constant 0.0039215689 represent?
I keep seeing this constant pop up in various graphics header files
0.0039215689
It seems to have something to do with color maybe?
Here is the first hit on Google:
void RDP_G_SETFOGCOLOR(void)
{
...
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answers
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Difference between char* and const char*?
What's the difference between
char* name
which points to a constant string literal, and
const char* name
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Constant pointer vs Pointer to constant [duplicate]
I want to know the difference between
const int* ptr;
and
int * const ptr;
and how it works.
It is pretty difficult for me to understand or keep remember this.
Please help.
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Declare a constant array
I have tried:
const ascii = "abcdefghijklmnopqrstuvwxyz"
const letter_goodness []float32 = { .0817,.0149,.0278,.0425,.1270,.0223,.0202, .0609,.0697,.0015,.0077,.0402,.0241,.0675, .0751,....
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'static const' vs. '#define'
Is it better to use static const variables than #define preprocessor? Or does it maybe depend on the context?
What are advantages/disadvantages for each method?
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How come a non-const reference cannot bind to a temporary object?
Why is it not allowed to get non-const reference to a temporary object,
which function getx() returns? Clearly, this is prohibited by C++ Standard
but I am interested in the purpose of such ...
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Why is 0 < -0x80000000?
I have below a simple program:
#include <stdio.h>
#define INT32_MIN (-0x80000000)
int main(void)
{
long long bal = 0;
if(bal < INT32_MIN )
{
printf("Failed!!!")...
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How to select multiple rows filled with constants?
Selecting constants without referring to a table is perfectly legal in an SQL statement:
SELECT 1, 2, 3
The result set that the latter returns is a single row containing the values. I was wondering ...
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Is it better in C++ to pass by value or pass by reference-to-const?
Is it better in C++ to pass by value or pass by reference-to-const?
I am wondering which is better practice. I realize that pass by reference-to-const should provide for better performance in the ...
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votes
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Ruby on Rails: Where to define global constants?
I'm just getting started with my first Ruby on Rails webapp. I've got a bunch of different models, views, controllers, and so on.
I'm wanting to find a good place to stick definitions of truly ...
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Why can I change a constant object in JavaScript?
I know that ES6 is not standardized yet, but a lot of browsers currently support const keyword in JS.
In spec, it is written that:
The value of a constant cannot change through re-assignment, and a
...
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How can I get all constants of a type by reflection?
How can I get all constants of any type using reflection?
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Why isn't String.Empty a constant?
In .NET why is String.Empty read only instead of a constant? I'm just wondering if anyone knows what the reasoning was behind that decision.
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Include constant in string without concatenating
Is there a way in PHP to include a constant in a string without concatenating?
define('MY_CONSTANT', 42);
echo "This is my constant: MY_CONSTANT";
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What is the temporal dead zone?
I've heard that accessing let and const values before they are initialized can cause a ReferenceError because of something called the temporal dead zone.
What is the temporal dead zone, how does it ...
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Go naming conventions for const [closed]
I'm trying to determine whether there is a naming convention for the names of const in Golang.
I personally would tend to follow the C style and write them in upper case, but I haven't found anything ...
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C++: const reference, before vs after type-specifier
What is the difference between the arguments in:
int foo1(const Fred &arg) {
...
}
and
int foo2(Fred const &arg) {
...
}
?
I don't see this case covered in the parashift FAQ.
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How to sort with a lambda?
sort(mMyClassVector.begin(), mMyClassVector.end(),
[](const MyClass & a, const MyClass & b)
{
return a.mProperty > b.mProperty;
});
I'd like to use a lambda function to sort ...
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What does the PHP error message "Use of undefined constant" mean?
PHP is writing this error in the logs: "Notice: Use of undefined constant".
Error in logs:
PHP Notice: Use of undefined constant department - assumed 'department' (line 5)
PHP Notice: Use of ...
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