[英]How to include a c++ library in a c project using Cmake
我是 c、c++ 和 Cmake 的初学者。
我从一个项目开始,该项目允许我将数据发送到用 C 编写的 Google Cloud IoT Core: https://github.com/espressif/esp-google-iot/blob/master/examples/smart_outlet/README .md
如您所见,我有一块带有 ESP32 芯片的电路板。
我买了一个我想使用的湿度传感器,并且库是用 c++ 编写的,因此将它们添加到 C 项目非常困难。 ( https://github.com/adafruit/DHT-sensor-library ) ( https://github.com/adafruit/Adafruit_Sensor )
我在我的 CMakeLists.txt 中导入这样的库:
cmake_minimum_required(VERSION 3.5)
include($ENV{IDF_PATH}/tools/cmake/project.cmake)
# This is some google iot librares that are being imported in the project
set (EXTRA_COMPONENT_DIRS "../..")
# Libraries in cpp that are not being compiled correctly
INCLUDE_DIRECTORIES(lib/Adafruit_Sensor)
LINK_DIRECTORIES(lib/Adafruit_Sensor)
INCLUDE_DIRECTORIES(lib/DHT-sensor-library)
LINK_DIRECTORIES(lib/DHT-sensor-library)
project(smart_outlet)
但是在编译 c++ 库时,我收到一条错误消息。
../lib/DHT-sensor-library/DHT_U.h:45:1: error: unknown type name 'class'
我认为抛出错误是因为 c 不支持 c++ 类。
这是向我抛出错误的 c++.h 文件:
#ifndef DHT_U_H
#define DHT_U_H
#include <Adafruit_Sensor.h>
#include <DHT.h>
#define DHT_SENSOR_VERSION 1 /**< Sensor Version */
/*!
* @brief Class that stores state and functions for interacting with
* DHT_Unified.
*/
class DHT_Unified {
public:
DHT_Unified(uint8_t pin, uint8_t type, uint8_t count = 6,
int32_t tempSensorId = -1, int32_t humiditySensorId = -1);
void begin();
/*!
* @brief Class that stores state and functions about Temperature
*/
class Temperature : public Adafruit_Sensor {
public:
Temperature(DHT_Unified *parent, int32_t id);
bool getEvent(sensors_event_t *event);
void getSensor(sensor_t *sensor);
private:
DHT_Unified *_parent;
int32_t _id;
};
/*!
* @brief Class that stores state and functions about Humidity
*/
class Humidity : public Adafruit_Sensor {
public:
Humidity(DHT_Unified *parent, int32_t id);
bool getEvent(sensors_event_t *event);
void getSensor(sensor_t *sensor);
private:
DHT_Unified *_parent;
int32_t _id;
};
/*!
* @brief Returns temperature stored in _temp
* @return Temperature value
*/
Temperature temperature() { return _temp; }
/*!
* @brief Returns humidity stored in _humidity
* @return Humidity value
*/
Humidity humidity() { return _humidity; }
private:
DHT _dht;
uint8_t _type;
Temperature _temp;
Humidity _humidity;
void setName(sensor_t *sensor);
void setMinDelay(sensor_t *sensor);
};
#endif
正如您在 github 存储库中看到的那样,这些文件具有 .cpp 和 .h 扩展名。
主项目有一个谷歌库的依赖,它是用嵌入式 c 编写的,并允许与谷歌云通信,到目前为止这还不是问题: https://github.com/GoogleCloudPlatform/iot-device-sdk-嵌入式-c
任何人都可以启发我如何做到这一点?
非常感谢!
是的,当我试图弄清楚如何通过 Cmake 链接 vs 库时,我的大脑也受到了伤害。
我是这样做的:
add_executable(exe_name main.cpp)
find_library(FLTK fltk /home/user/proj/fltk/fltk/lib)
find_library(FLTK_IMG fltk_images /home/user/proj/fltk/fltk/lib)
target_link_libraries(exe_name LINK_PUBLIC ${FLTK} ${FLTK_IMG} ${LINK_FLAGS})
所以对你来说,我认为你需要一个find_library
但你必须指定库名称:
find_library(AF_SENSOR Adafruit_Sensor lib)
find_library(DHT_SENSOR DHT_sensor-library lib)
target_link_libraries(exe_name LINK_PUBLIC ${AF_SENSOR} ${DHT_SENSOR})
我猜“Adafruit_Sensor”是实际的.lib 文件等。您可能需要 find_library() 的第三个参数的完整路径...
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