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<h1>Why can't a class have a non-integral static const member?</h1>
<p>When it comes to coding in C++, there are certain rules and restrictions that must be followed in order to ensure the code is efficient and error-free. One of these rules pertains to the use of static const members in a class. In particular, the restriction states that a class cannot have a non-integral static const member. But why is this the case? Let's dive deeper into the reasons behind this limitation.</p>
<h2>The Basics of Static Const Members</h2>
<p>Before we can understand why a class can't have a non-integral static const member, it's important to first understand what these terms mean. In simple terms, a static member is a member of a class that is shared by all instances of that class. This means that the value of the member remains the same for all objects of that class. A const member, on the other hand, is a member that cannot be modified once it has been initialized. It is essentially a constant value.</p>
<p>So, when we talk about a static const member, we are referring to a member of a class that is both shared by all instances and cannot be modified. This is a useful feature in C++ as it allows for the creation of global variables that can be accessed by all objects of a class without the risk of being modified. However, there is a caveat to this rule when it comes to non-integral values.</p>
<h2>The Limitation of Non-Integral Values</h2>
<p>In C++, there are two types of data: integral (whole numbers) and non-integral (numbers with decimal points). When it comes to static const members, the restriction only applies to non-integral values. This means that a class can have a static const member that is an integer, but not one that is a float or double.</p>
<p>So why is this the case? The main reason is related to the initialization of static const members. In C++, static const members must be initialized at the point of declaration. This means that their value cannot be assigned at a later time. This is not an issue for integral values as they can be assigned a value at the point of declaration. However, non-integral values require a more complex initialization process, which cannot be done at the point of declaration. This creates a conflict with the rule that static const members must be initialized at the point of declaration.</p>
<h2>The Workaround</h2>
<p>While the restriction on non-integral static const members may seem limiting, there is a workaround that can be used. Instead of declaring the member as a const, it can be declared as a constexpr. Constexpr stands for "constant expression" and it allows for the initialization of non-integral values at the point of declaration. This means that the value of the member can be assigned at the same time it is declared, bypassing the conflict with the rule for static const members.</p>
<p>However, this workaround does come with its own limitations. Constexpr members are required to be basic types, which means they cannot be objects or complex types. They must also be initialized with a constant expression, which can be restrictive in some cases.</p>
