What are the arguments for and against making identifiers case sensitive in programming language?

Answer 1

The simple argument for case-sensitivity is that character 'A' (#65) and character 'a' (#97) are not the same character. To us humans they are clearly the same letter, but computers are less forgiving. Back in the good old days when RAM and CPU time were expensive, it simply wasn't worth the effort or expense to have the computer treat them as being the same. In those days, the onus was largely upon the programmer to ensure they identified variables correctly. Programmers were far more concerned with speed of compilation and, having been brought up within the case-sensitive world of Unix, they were intelligent enough to know that MAX and max are not the same identifier as far as the computer was concerned.

As the cost of computing fell and more and more people wanted to program them, the unforgiving nature of case-sensitive programming became a greater concern, thus languages such as BASIC were developed to address the problem and make life easier for newcomers. The same can be said of DOS, from which MS-DOS evolved. But while these languages and operating systems are more forgiving, they lack the flexibility and speed of a case-sensitive environment.

In C, for instance, the inherent case-sensitivity makes it possible to use programming conventions such as all uppercase for macro identifiers and lowercase for C identifiers. Macros are not actually part of the C language -- they are used by the preprocessor to prepare the C source code for compilation -- but it is helpful to be able to differentiate a macro from an actual identifier in your code, even when they have the exact same name.

MAX and max are not the same, but then neither is Max or mAx. Normally you wouldn't use mixed-case like this in C, as it makes your code hard to read, but the language is flexible enough to permit it should you wish to do so. And that is the main advantage: flexibility. The main disadvantage is the lack of forgiveness. But if you want forgiveness, you wouldn't be programming in C to begin with, you'd use something far more abstract instead, like Visual Basic.