Enabling __int128 in Visual Studio: Is It Possible?

Despite appearing as a keyword in Visual Studio's code editor, __int128 fails to compile with an error message indicating it's not supported on the current architecture.

The Official Stance

According to the Microsoft Developer Network (MSDN) documentation, __int128 is not listed as an available data type. Additionally, the error message confirms this by stating that the keyword is not supported.

Syntax Highlighting is Not Trustworthy

Code syntax highlighters, like the one in Visual Studio, can sometimes display syntax that is not yet implemented or is reserved for future use. Therefore, it's not advisable to rely solely on syntax highlighting as an indication of supported features.

128-Bit Data Types

Currently, the only 128-bit data types available in Visual Studio are SIMD types, such as __m128. These types span across multiple registers to create wider data types.

Alternative Solutions

Although __int128 is not directly supported, there are other ways to work with 128-bit integers on compatible platforms:

• By utilizing compiler extensions or third-party libraries that provide support for __int128.
• By using SIMD types to perform 128-bit integer operations.