我有三个文件:包括问题:“多重定义”,“先在这里定义的”
main.cpp
MyClass.cpp
MyClass.hpp
我有一个库的头文件,"testLib.hpp"
,我想在MyClass.hpp
包括这样我可以有一个testLib的对象是类属性。
我在MyClass.cpp
和main.cpp
中包括MyClass.hpp
。当尝试编译项目,我收到以下错误
MyClass.cpp multiple definition of 'testLib::testLib::function1()
obj/Release/main.o:main.cpp first defined here
MyClass.cpp multiple definition of 'testLib::testLib::function2()
obj/Release/main.o:main.cpp first defined here
等。
main.cpp
和MyClass.cpp
都包括MyClass.hpp
(其包括testLib.hpp
)。从错误判断,看起来MyClass.cpp
正试图在库函数已包含在main.cpp
之后。不过,我已经包括了目前在0的警卫,所以我不明白它是如何试图包括MyClass.hpp
两次。
下面的代码:
MyClass.hpp
#ifndef THIS_HEADER_H
#define THIS_HEADER_H
#include <stdint.h>
#include <iostream>
#include "testLib/testLib.hpp"
class MyClass
{
public:
void test();
int foo;
private:
uint32_t bar;
//I want to include an object from the library as part of this class
//TestLib::Device device;
};
#endif
MyClass.cpp
#include <stdio.h>
#include "MyClass.hpp"
void MyClass::test()
{
}
的main.cpp
#include <iostream>
#include "MyClass.hpp"
using namespace std;
int main()
{
cout << "Hello world!" << endl;
return 0;
}
任何帮助将不胜感激!
编辑 我试图隐藏实际的文件名,使问题更普遍的和明确的,但似乎问题可能来自“testLib.hpp”,这是我没有写来产生。该文件实际上是以下“sweep.hpp”文件。我得到了“的多个定义/在这里先定义”的错误为每个在此文件中的公共职能:
sweep.hpp
#ifndef SWEEP_DC649F4E94D3_HPP
#define SWEEP_DC649F4E94D3_HPP
/*
* C++ Wrapper around the low-level primitives.
* Automatically handles resource management.
*
* sweep::sweep - device to interact with
* sweep::scan - a full scan returned by the device
* sweep::sample - a single sample in a full scan
*
* On error sweep::device_error gets thrown.
*/
#include <cstdint>
#include <memory>
#include <stdexcept>
#include <vector>
#include <sweep/sweep.h>
namespace sweep {
// Error reporting
struct device_error final : std::runtime_error {
using base = std::runtime_error;
using base::base;
};
// Interface
struct sample {
const std::int32_t angle;
const std::int32_t distance;
const std::int32_t signal_strength;
};
struct scan {
std::vector<sample> samples;
};
class sweep {
public:
sweep(const char* port);
sweep(const char* port, std::int32_t bitrate);
void start_scanning();
void stop_scanning();
bool get_motor_ready();
std::int32_t get_motor_speed();
void set_motor_speed(std::int32_t speed);
std::int32_t get_sample_rate();
void set_sample_rate(std::int32_t speed);
scan get_scan();
void reset();
private:
std::unique_ptr<::sweep_device, decltype(&::sweep_device_destruct)> device;
};
// Implementation
namespace detail {
struct error_to_exception {
operator ::sweep_error_s*() { return &error; }
~error_to_exception() noexcept(false) {
if (error) {
device_error e{::sweep_error_message(error)};
::sweep_error_destruct(error);
throw e;
}
}
::sweep_error_s error = nullptr;
};
}
sweep::sweep(const char* port)
: device{::sweep_device_construct_simple(port, detail::error_to_exception{}), &::sweep_device_destruct} {}
sweep::sweep(const char* port, std::int32_t bitrate)
: device{::sweep_device_construct(port, bitrate, detail::error_to_exception{}), &::sweep_device_destruct} {}
void sweep::start_scanning() { ::sweep_device_start_scanning(device.get(), detail::error_to_exception{}); }
void sweep::stop_scanning() { ::sweep_device_stop_scanning(device.get(), detail::error_to_exception{}); }
bool sweep::get_motor_ready() { return ::sweep_device_get_motor_ready(device.get(), detail::error_to_exception{}); }
std::int32_t sweep::get_motor_speed() { return ::sweep_device_get_motor_speed(device.get(), detail::error_to_exception{}); }
void sweep::set_motor_speed(std::int32_t speed) {
::sweep_device_set_motor_speed(device.get(), speed, detail::error_to_exception{});
}
std::int32_t sweep::get_sample_rate() { return ::sweep_device_get_sample_rate(device.get(), detail::error_to_exception{}); }
void sweep::set_sample_rate(std::int32_t rate) {
::sweep_device_set_sample_rate(device.get(), rate, detail::error_to_exception{});
}
scan sweep::get_scan() {
using scan_owner = std::unique_ptr<::sweep_scan, decltype(&::sweep_scan_destruct)>;
scan_owner releasing_scan{::sweep_device_get_scan(device.get(), detail::error_to_exception{}), &::sweep_scan_destruct};
auto num_samples = ::sweep_scan_get_number_of_samples(releasing_scan.get());
scan result;
result.samples.reserve(num_samples);
for (std::int32_t n = 0; n < num_samples; ++n) {
auto angle = ::sweep_scan_get_angle(releasing_scan.get(), n);
auto distance = ::sweep_scan_get_distance(releasing_scan.get(), n);
auto signal = ::sweep_scan_get_signal_strength(releasing_scan.get(), n);
result.samples.push_back(sample{angle, distance, signal});
}
return result;
}
void sweep::reset() { ::sweep_device_reset(device.get(), detail::error_to_exception{}); }
} // ns
#endif
您是否尝试过#pragma一次 –
包含防护措施会阻止将同一个头文件包含在同一个源中两次。它们不会阻止将相同的头文件包含到多个源文件中(它们也不应该;这正是头文件的预期用法)。主要的错误是'testLib.hpp'头文件定义了几个函数。一个头文件只应该声明函数(应该在某个源文件中定义);或者用'inline'关键字来定义它们。 –
@IgorTandetnik感谢您的回复。我在原始文章中包含了我命名为'testLib.hpp'的实际库文件(sweep.hpp)。我没有写sweep.hpp。看起来他们确实声明了一些我得到错误的功能。所以你说这个错误完全来自sweep.hpp? – user3878723