## 检测python解释器

```txt
cmake_minimum_required(VERSION 3.5 FATAL_ERROR)
project(wang5)

#找到python解释器
find_package(PythonInterp REQUIRED)

#执行python命令并捕获它的输出和返回值
execute_process(COMMAND ${PYTHON_EXECUTABLE} "-c" "print('wangyuedong')"
    RESULT_VARIABLE _status
    OUTPUT_VARIABLE _output
    ERROR_QUIET
    OUTPUT_STRIP_TRAILING_WHITESPACE
)

#将输出打印到屏幕
message(STATUS "RESULT_VARIABLE is: ${_status}")
message(STATUS "OUTPUT_VARIABLE is: ${_output}")
```

## 检测python库

以上使用python解释器来操作程序的输出，然后可以更高级一点，将解释语言python和编译语言C++组合到一起使用。有两种做法，第一种是扩展python，通过编译成共享库的C和C++模块提供新类型和方法。第二种是将python解释器嵌入到C和C++的程序中。两种方式都需要一些条件才可以实现。

- Python解释器的工作版本；
- Python头文件python.h可用；
- Python运行时库libpython。

这三个组件使用的python版本必须相同。

下面演示一下第二种方式，将python解释器嵌入到C程序中，程序wang_embedded_python.c。此代码将在程序中初始化Python解释器的实例，并使用Python的`time`模块，打印日期。

```c
#include <Python.h>

int main(int argc, wchar_t *argv[])
{
	Py_SetProgramName(argv[0]);
	Py_Initialize();
	PyRun_SimpleString("from time import time, ctime\n"
		"print('Today is', ctime(time()))");
	Py_Finalize();
	return 0;
}

```

编写 CMakeLists.txt

```bash
cmake_minimum_required(VERSION 3.5 FATAL_ERROR)

project(wang5 LANGUAGES C)

set(CMAKE_C_STANDARD 99)
set(CMAKE_C_EXTENSIONS OFF)
set(CMAKE_C_STANDARD_REQUIRED ON)


find_package(PythonInterp 3.5)
find_package(PythonLibs ${PYTHON_VERSION_MAJOR}.${PYTHON_VERSION_MINOR} EXACT REQUIRED)

add_executable(wang5 wang_embedded_python.c)

target_include_directories(wang5 PRIVATE ${PYTHON_INCLUDE_DIRS})
target_link_libraries(wang5 PRIVATE ${PYTHON_LIBRARIES})

```

cmake配置，make编译后的生成可执行文件 wang5。

```bash
./wang5
Today is Thu Apr 14 16:17:01 2022
```

## 检测Python模块和包

前面的示例中，我们演示了如何检测Python解释器，以及如何编译一个简单的C程序(嵌入Python解释器)。通常，代码将依赖于特定的Python模块，无论是Python工具、嵌入Python的程序，还是扩展Python的库。科学界非常流行使用NumPy处理矩阵问题。依赖于Python模块或包的项目中，确定满足对这些Python模块的依赖非常重要。本示例将展示如何探测用户的环境，以找到特定的Python模块和包。




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