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c++floating-pointhex

Hexadecimal floating point literals

Is it possible to initialize a float variable with a hexadecimal float point value in C++?

Something like this:

double d = 0x011.1; // wrong!
Solution

  • No, C++ doesn't support that for literals, it's not part of the standard in 2014.*

    A non-portable solution is to use a compiler that adds this as an extension (GCC does this).

    A portable workaround is to parse them from string literals at runtime using e.g. strtof() or strtod() for double.

    As pointed out in a comment, you can also opt to store the constants in a C file. Doing so requires that you have access to a C99 compiler though, since hex float literals is a C99-level feature. Since environments with a new C++ compiler but without a C99 compiler (read: Visual Studio) are quite common, that might not be a workable solution.

    * Addition in 2019: C++17 supports hexadecimal floating point literals.