A shared syntax across otherwise different languages
The 0x-prefixed hex literal is one of the more consistent pieces of syntax across modern programming languages, tracing back to C, which popularized the convention decades ago. C#, Java, JavaScript, and Python all accept 0xFF as a valid way to write the integer 255 directly in source code, with no parsing function required — the compiler or interpreter recognizes the prefix and converts it automatically. That shared syntax is exactly why this tool can generate a working snippet for four different languages from the same hex input: the literal itself doesn't need to change between languages, only the surrounding variable declaration and comment syntax do.
What actually differs between the four languages
The visible differences in the generated snippets are mostly about declaration syntax, not about the hex literal itself. C# and Java both require an explicit type (int value = ...) because they're statically typed. JavaScript uses const since it doesn't require (or have) a static integer type — a JavaScript number holds the value regardless of whether it originated from a hex or decimal literal. Python omits a type declaration entirely and uses # for its comment syntax rather than //. These surface differences are exactly the kind of small, easy-to-mistype detail that makes copy-pasting a working, correctly-formatted snippet more convenient than retyping the same value by hand in each language's own syntax.
What this tool deliberately doesn't model
Integer size and overflow behavior differ substantially between these languages, and this tool doesn't attempt to simulate that. Java's int is a fixed 32-bit signed type — a hex literal larger than 0x7FFFFFFF assigned to a plain int would overflow or require along instead. Python's integers have arbitrary precision and never overflow. JavaScript's numbers are IEEE 754 doubles, which lose precision for integers beyond 2^53. C#'s intbehaves like Java's. None of that size-dependent behavior is reflected in the generated snippet, which is a plain literal assignment — for very large hex values, the correct type per language (Java'slong, C#'s long, or Python's default arbitrary-precision int) should be chosen based on the target language's actual rules, not assumed from this tool's output.
Why generate a snippet instead of just showing the decimal value
The site's main Hex ↔ Decimal converter already shows the plain numeric equivalent of a hex value. This tool exists for a different, narrower purpose: producing code that's ready to paste directly into a source file, with correct syntax for the target language, rather than requiring the decimal or hex value to be manually inserted into a hand-typed variable declaration. That's a small convenience in isolation, but a meaningful one when working through many values — porting a list of constants from a specification document into source code, for instance, where retyping each declaration by hand is both slow and a place where small syntax mistakes creep in.
Case conventions across languages
This tool outputs hex digits in uppercase (0xFF rather than 0xff), which is valid in every one of the four supported languages — case never affects the value of a hex literal, only its appearance. Style guides differ on preference: some codebases favor uppercase for visual distinction from surrounding lowercase code, others favor lowercase to match how hex hash digests and many external APIs render values. Neither is a functional requirement in any of these languages, so the choice is purely a formatting convention that can be safely changed after pasting if a project's style guide specifies otherwise.
Batch generation across a language's constants
Batch mode applies the currently-selected language to every hex value in a pasted list, producing one ready-to-paste snippet line per value — useful for converting an entire block of hex constants (register addresses, protocol magic numbers, color values) into source-code declarations for a single target language in one pass, exportable as CSV for further editing before pasting into a codebase.