CUDA错误：名称后跟“ ::”必须是类或名称空间

Question

[我正在开发我的第一个CUDA程序，并使用nvcc编译器遇到了错误，而如果使用g++进行编译，则不会遇到此错误。

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;
}

如果我使用nvcc test.cu -o test进行编译，则结果为：

/usr/include/c++/5/bits/stl_iterator_base_types.h(168): error: name followed by "::" must be a class or namespace name
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
test.cu(11): here

/usr/include/c++/5/bits/stl_iterator_base_types.h(169): error: name followed by "::" must be a class or namespace name
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
test.cu(11): here

/usr/include/c++/5/bits/stl_iterator_base_types.h(170): error: name followed by "::" must be a class or namespace name
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
test.cu(11): here

/usr/include/c++/5/bits/stl_iterator_base_types.h(171): error: name followed by "::" must be a class or namespace name
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
test.cu(11): here

/usr/include/c++/5/bits/stl_iterator_base_types.h(172): error: name followed by "::" must be a class or namespace name
          detected during instantiation of class "std::iterator_traits<_Iterator> [with _Iterator=double]" 
test.cu(11): here

当我将文件扩展名更改为.cpp并按以下方式编译时，g++ test.cpp -o test，代码将遵循。如果然后执行./test，则会得到所需的结果：

distance = 6

[看this帖子激发了我考虑我是否从主机/设备划分的错误方面调用某些内容的可能性，但是，我尚未进行任何GPU调用。

不确定发生了什么，但是到目前为止，CUDA编译器似乎非常挑剔。

Answer 1

您需要将-std=c++11选项添加到nvcc进行编译。通过使用std命名空间，您与std::distance发生冲突，而这需要c ++ 11或更高版本才能使用nvcc进行编译。