How to Determine if a C Compiler Adheres to the IEEE 754 Standard?

Determining Compiler's Use of IEEE 754 Standard in C

Unlike C, which requires a specific define check to verify if the compiler adheres to the IEEE 754 standard, C offers a more straightforward approach. The C standard includes the numeric_limits class within the std namespace. To determine if the compiler employs IEEE 754, simply access the static member is_iec559 as follows:

<code class="cpp">std::numeric_limits<double>::is_iec559;</code>

or:

<code class="cpp">std::numeric_limits<float>::is_iec559;</code>

This expression returns true if IEEE 754 is in use, and false otherwise.

Alternatively, as suggested by Adam's answer, you can also employ another method:

<code class="cpp">#include <iostream>
#include <cmath>

int main() {
    double d = -0.0;
    std::cout << (std::signbit(d) != std::signbit(-d)) << std::endl;
    return 0;
}</code>

If the compiler supports IEEE 754, this code outputs 0; otherwise, it outputs 1.

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