std::numeri...ts::is_exact(3)

💅 std::numeric_limits::is_exact(3)

okay so picture this: we're deep in the C++ Standard Libary man pages (yes that's literally how it's spelled up top, don't come for me 🙈) and we're here to talk about one tiny little static member that answers a very important question: "bestie, does your number type keep it 💯 exact?"

✨ NAME ✨

std::numeric_limits::is_exact — literally just std::numeric_limits::is_exact, she's self-titled, main character energy 👑

🎀 Synopsis 🎀

static const bool is_exact;      (until C++11)
static constexpr bool is_exact;  (since C++11)

The way this works is so simple it's giving minimalist: the value of std::numeric_limits<T>::is_exact is true for all arithmetic types T that use exact representation. That's it. That's the whole vibe. ✨

🌸 Standard specializations 🌸

here's the full roll call, no skips, no cuts, everybody gets a line 💖

• /* non-specialized */ — false
• bool — true
• char — true
• signed char — true
• unsigned char — true
• wchar_t — true
• char8_t (since C++20) — true
• char16_t (since C++11) — true
• char32_t (since C++11) — true
• short — true
• unsigned short — true
• int — true
• unsigned int — true
• long — true
• unsigned long — true
• long long (since C++11) — true
• unsigned long long (since C++11) — true
• float — false
• double — false
• long double — false

so the integers ate and left no crumbs, and the floating point girlies are sitting at false — that's the whole energy of this table 🫶

🦋 Notes 🦋

okay real talk, here's the little caveat that lives in the footnotes: while all fundamental types T for which std::numeric_limits<T>::is_exact == true are integer types, a library may define exact types that are not integers — for example, a rational arithmetic type representing fractions. so like, exact ≠ automatically integer, iykyk 😌

💜 See also 💜

• is_integer — identifies integer types — [static] (public static member constant)
• is_signed — identifies signed types — [static] (public static member constant)
• is_bounded — identifies types that represent a finite set of values — [static] (public static member constant)

💀 friendly reminder: everything above is descriptive, so don't go assuming an exact type is an integer just because every fundamental one happens to be. read the Notes section, bestie, it's there for a reason.

and that's the page!! source is http://cppreference.com, dated 2024.06.10, filed under std::numeric_limits::is_exact(3) — go off and check your types, mwah 💅🎀✨