C++ CUDA错误：名称后面跟着“：”&引用；必须是类或命名空间

我正在编写我的第一个CUDA程序，使用

nvcc

编译器时遇到了错误，如果我使用

g++

编译，就不会遇到这种情况

我的代码：

#include <iostream>
#include <cmath>

using namespace std;

double distance(double first, double second);

int main(){
   double dis;
   dis = distance(7.0, 1.0);
   cout << "distance = " << dis << endl;
   return 0;
}

double distance(double first, double second){
   double diff;
   diff = abs(first-second);
   return diff;
}

当我将文件扩展名更改为.cpp并按如下方式编译时，

g++test.cpp-o test

，代码符合要求。如果然后执行

/test

，我会得到我想要的结果：

distance = 6

查看帖子启发我考虑从主机/设备划分错误的地方调用一些东西的可能性，但是，我现在还没有做任何GPU调用。p>

---

不确定发生了什么，但到目前为止，CUDA编译器似乎非常挑剔。

您需要将

-std=c++11

选项添加到nvcc以编译此代码。通过使用std名称空间，您会与

std:：distance

发生冲突，这需要c++11或更高版本使用nvcc进行编译

这项工作：

$ cat bugaboo.cu
#include <iostream>
#include <cmath>

using namespace std;

double distance(double first, double second);

int main(){
   double dis;
   dis = distance(7.0, 1.0);
   cout << "distance = " << dis << endl;
   return 0;
}

double distance(double first, double second){
   double diff;
   diff = abs(first-second);
   return diff;
}

$ nvcc --version
nvcc: NVIDIA (R) Cuda compiler driver
Copyright (c) 2005-2018 NVIDIA Corporation
Built on Tue_Jun_12_23:07:04_CDT_2018
Cuda compilation tools, release 9.2, V9.2.148

$ nvcc --std=c++11 -o bugaboo bugaboo.cu

$ ./bugaboo
distance = 6

$cat bugaboo.cu
#包括
#包括
使用名称空间std；
双倍距离（双倍第一、双倍第二）；
int main（）{
双dis；
dis=距离（7.0,1.0）；
cout Off-topic:About…Hm，如果再次阅读错误消息，我之前的评论似乎没有最初出现的那么离题-已经有了，并且您自己的
distance
函数似乎与…@Aconcagua发生了冲突，您解决了！将我的函数名更改为
dist（…）
解决了这个问题。更好的方法是：不要使用
命名空间std；
如果编写
std:：cout
对你来说确实太多了，那么就改用
使用std:：cout；
吧。你可以在你自己的命名空间中另外放置你自己的函数。@Acocagua这里有一个建议：如果你非常愿意帮助学习如果你想对某人的问题发表评论，试着用一种不会让人觉得是屈尊俯就的方式来做。提示：请记住，有些人对软件开发和/或特定编程语言是新手。
$ cat bugaboo.cu
#include <iostream>
#include <cmath>

using namespace std;

double distance(double first, double second);

int main(){
   double dis;
   dis = distance(7.0, 1.0);
   cout << "distance = " << dis << endl;
   return 0;
}

double distance(double first, double second){
   double diff;
   diff = abs(first-second);
   return diff;
}

$ nvcc --version
nvcc: NVIDIA (R) Cuda compiler driver
Copyright (c) 2005-2018 NVIDIA Corporation
Built on Tue_Jun_12_23:07:04_CDT_2018
Cuda compilation tools, release 9.2, V9.2.148

$ nvcc --std=c++11 -o bugaboo bugaboo.cu

$ ./bugaboo
distance = 6

$ nvcc -o bugaboo bugaboo.cu
/usr/include/c++/4.8/bits/stl_iterator_base_types.h(165): error: a class or namespace qualified name is required
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(165): error: global-scope qualifier (leading "::") is not allowed
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(165): error: expected a ";"
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(166): error: a class or namespace qualified name is required
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(166): error: global-scope qualifier (leading "::") is not allowed
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(166): error: expected a ";"
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(167): error: a class or namespace qualified name is required
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(167): error: global-scope qualifier (leading "::") is not allowed
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(167): error: expected a ";"
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(168): error: a class or namespace qualified name is required
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(168): error: global-scope qualifier (leading "::") is not allowed
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(168): error: expected a ";"
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(169): error: a class or namespace qualified name is required
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(169): error: global-scope qualifier (leading "::") is not allowed
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

/usr/include/c++/4.8/bits/stl_iterator_base_types.h(169): error: expected a ";"
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
bugaboo.cu(10): here

15 errors detected in the compilation of "/tmp/tmpxft_00000acd_00000000-8_bugaboo.cpp1.ii".