Why use constants in programming? [closed]

Answer 1

Constant is when you just want to share the memory, and it doesn't change.

Answer 2

For one, performance optimization.

More importantly, this is for human readers. Remember that your target audience is not only the compiler. It helps to express yourself in code, and avoid comments.

const int spaceTimeDimensions = 4;

if(gpsSattelitesAvailable >= spaceTimeDimensions)
  Good();

Answer 3

For a low-level language like C, constants allow for several compilation optimizations.

For a programming language in general, you don't really need them. High level dynamic languages such as Ruby and JavaScript doesn't have them (or at least not in a true constant sense). Variables are used instead, just like you suggested.

Answer 4

The const keyword is often used for function parameters, particularly pointers, to suggest the memory the pointer points to will not be modified by the function. Look at the decleration for strcpy for instance:

char *strcpy(char *dest, const char *src);

Otherwise, for example, an declaration such as

const int my_magic_no = 54321;

might be preferred over:

#define MY_MAGIC_NO 54321

for type safety reasons.