> ## Documentation Index > Fetch the complete documentation index at: https://docs.syntblaze.com/llms.txt > Use this file to discover all available pages before exploring further. # C++ char16_t `char16_t` is a fundamental, distinct character type in C++ introduced in C++11, specifically designed to represent 16-bit wide characters and serve as the standard language-level type for UTF-16 encoded code units. ## Type Characteristics * **Underlying Representation:** `char16_t` is guaranteed by the C++ Standard to have the exact same size, signedness, and alignment requirements as `std::uint_least16_t` (defined in ``). * **Signedness:** It is strictly an unsigned type. * **Size:** It is guaranteed to be at least 16 bits wide. Because the `sizeof` operator returns the size in C++ bytes (where one byte is defined as `CHAR_BIT` bits), `sizeof(char16_t)` is not strictly guaranteed to be 2. On systems where `CHAR_BIT` is 8, `sizeof(char16_t)` is 2; however, on systems where `CHAR_BIT` is 16 or greater, `sizeof(char16_t)` evaluates to exactly 1. * **Type Distinctness:** `char16_t` is a distinct type, not a typedef. While it shares the memory layout of `std::uint_least16_t`, it is treated as a unique type by the compiler for the purposes of function overloading and template instantiation. * **Platform Consistency:** Unlike `wchar_t`, whose size is implementation-defined (typically 16 bits on Windows and 32 bits on POSIX systems), `char16_t` provides a strict cross-platform guarantee regarding its minimum bit width and intended encoding. ## Syntax and Literals To declare a `char16_t` character or string literal, prefix the literal with a lowercase `u`. ```cpp theme={"dark"} // Character literal (must fit within a single 16-bit code unit) char16_t ascii_char = u'A'; char16_t unicode_char = u'\u00DF'; // U+00DF (ß) // String literal (deduced as an array of const char16_t) const char16_t* str = u"UTF-16 encoded string literal"; // Surrogate pairs (characters outside the Basic Multilingual Plane) // require two char16_t code units, so they cannot be stored in a single char16_t. // They must be stored in an array or string. const char16_t* emoji = u"\U0001F600"; // U+1F600 (😀) - takes two char16_t elements ``` ## Standard Library Integration The C++ Standard Library provides specialized aliases and traits to support `char16_t` operations, primarily found in the `` and `` headers. ```cpp theme={"dark"} #include #include // Alias for std::basic_string, std::allocator> std::u16string dynamic_str = u"Managed UTF-16 string"; // Alias for std::basic_string_view> (C++17) std::u16string_view str_view = u"Non-owning UTF-16 string view"; ``` Standard stream objects (like `std::cout`) do not have overloaded insertion operators (`<<`) for `char16_t` or `std::u16string`. Outputting these types directly requires explicit conversion to a supported character type (like `char`) or the use of standard library conversion facets.

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