devxlogo

Creating Immutable Constants

Although usually I don’t recommend using macros in C++ code, there are a few exceptions. One such exception is when you want to create a truly immutable constant. Consider the following constant:

   const int MAX=512;

Seemingly, MAX’s value can’t be changed because it’s const. However, on some platforms, a brute-force cast can change its value. For example:

   int *p = const_cast (&MAX); // remove constness  *p= 100; // attempt to change MAX through a pointer

Although any attempt to change a const object causes undefined behavior according to the C++ standard, some compilers let this hack pass unnoticed. To disable such possible hacks altogether, you can use a macro instead of a const object:

   #define MAX 512

This time, MAX can’t be changed.

Charlie has over a decade of experience in website administration and technology management. As the site admin, he oversees all technical aspects of running a high-traffic online platform, ensuring optimal performance, security, and user experience.

See also  Five Early Architecture Decisions That Quietly Get Expensive

About Our Editorial Process

At DevX, we’re dedicated to tech entrepreneurship. Our team closely follows industry shifts, new products, AI breakthroughs, technology trends, and funding announcements. Articles undergo thorough editing to ensure accuracy and clarity, reflecting DevX’s style and supporting entrepreneurs in the tech sphere.

See our full editorial policy.