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Questions tagged [compile-time-constant]

Use this tag for questions related to the compile time constant, a constant value that is known at compile time.

A expression is an expression denoting a value of primitive type or a String that is composed using only the following:

is uses in its general meaning, but you should provide the relevant tag of your programming environment, if any.

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Java switch statement: Constant expression required, but it IS constant

So, I am working on this class that has a few static constants: public abstract class Foo { ... public static final int BAR; public static final int BAZ; public static final int BAM; ... } Then, I would like a way to get a…
Austin Hyde
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How to declare a constant Guid in C#?

Is it possible to declare a constant Guid in C#? I understand that I can declare a static readonly Guid, but is there a syntax that allows me to write const Guid?
smartcaveman
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constexpr overloading

Related: Function returning constexpr does not compile I feel like constexpr is limited in usefulness in C++11 because of the inability to define two functions that would otherwise have the same signature, but have one be constexpr and the other not…
David Stone
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M_PI flagged as undeclared identifier

When I compile the code below, I got these error messages: (Error 1 error C2065: 'M_PI' : undeclared identifier 2 IntelliSense: identifier "M_PI" is undefined) What is this? #include #include using namespace std; double…
Eunsu Kim
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Compile-time constants and variables

The Java language documentation says: If a primitive type or a string is defined as a constant and the value is known at compile time, the compiler replaces the constant name everywhere in the code with its value. This is called a compile-time …
AllTooSir
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Why isn't a final variable always a constant expression?

In the below code: final int a; a=2; byte b=a; // error: possible loss of precision Why do I get this error? Isn't a final variable compile time constant expression and hence implicitly narrowed to byte during the assignment? In other words isn't…
paidedly
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Dividing by zero in a constant expression

My toy compiler crashes if I divide by zero in a constant expression: int x = 1 / 0; Is this behaviour allowed by the C and/or C++ standards?
fredoverflow
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What's the difference between equ and db in NASM?

len: equ 2 len: db 2 Are they the same, producing a label that can be used instead of 2? If not, then what is the advantage or disadvantage of each declaration form? Can they be used interchangeably?
paxdiablo
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Why isn't std::string::max_size a compile-time constant?

std::string provides a max_size() method to determine the maximum number of elements it can contain. However, to work out the maximum length of a string in general, the programmer has to create a (possibly empty) string object. If this class doesn't…
slaphappy
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Constant expression contains invalid operations

I have the following code, where I get the error "PHP Fatal Error: Constant expression contains invalid operations". It works fine when I define the variable in the constructor. I am using Laravel framework.
Aaron
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C# - Why are DateTime.MinValue and MaxValue not compile-time constants?

I wanted to have an optional date parameter for a method (defaulted to MinValue), in order to check if the user had actually supplied a value or not (supplying MinValue was invalid), but I'm not allowed as apparently it's not a compile-time…
Alex
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Compiletime build up of std::regex

Since I know the regexes at compiletime, and building up a regex is in O(2^m) where m is the length of the regex, I would love to build up the regex at compiletime. Is this possible with std::regex? (I don't think so, because I don't see any…
Exagon
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Difference between final variables and compile time constant

What is the difference between final variables and compile time constants? Consider the following code final int a = 5; final int b; b=6; int x=0; switch(x) { case a: //no error case b: //compiler error } What does this mean? When and how…
Tarun Mohandas
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Are all compile-time constants inlined?

Let's say I have a class like this: class ApplicationDefs{ public static final String configOption1 = "some option"; public static final String configOption2 = "some other option"; public static final String configOption3 = "yet another…
Saravanan M
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Delphi: All constants are constant, but some are more constant than others?

Consider: const clHotlight: TColor = $00FF9933; clLink = clHotLight; //alias of clHotlight [Error] file.pas: Constant expression expected and the alternate wording that works: const clHotlight = TColor($00FF9933); clLink =…
Ian Boyd
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