# <version>

**[<version>](https://en.cppreference.com/w/cpp/header/version)** provides `__cpp_*` feature-test macros (C++20) that tell you which C++ features are available in your compiler and standard library. For example, `__cpp_concepts` is defined if C++20 concepts are supported.

Use these in preprocessor conditionals to enable features selectively.

## Example

This example uses feature-test macros to conditionally report whether C++20 concepts and ranges are supported by the compiler.

```cpp
// compile: g++ -std=c++20 -o versionexample versionexample.cpp
// run: ./versionexample
// description: check for C++ features

#include <version>
#include <iostream>

int main() {
#ifdef __cpp_concepts
    std::cout << "concepts supported\n";
#endif

#ifdef __cpp_ranges
    std::cout << "ranges supported\n";
#endif

    return 0;
}
```