Ubuntu 14.04上的Eclipse C ++找不到字符串的stod（） [英] Eclipse C++ on Ubuntu 14.04 cannot find string's stod()

问题描述

Elipse如果包含对字符串函数stod（）的调用，则无法在我的系统上构建C ++程序。我正在使用C / C ++透视图在Eclipse上运行Ubuntu 14.04。

我已经包含了标头，并使用-std = c ++ 11编译标志进行了编译并进行了设置从gcc到g ++的编译器，但是没有用。我还尝试使用Eclipse的 ISO C ++ 11方言设置（将编译标志设置为-std = c ++ 0x。在所有情况下，编译器都无法看到stod函数。

要找出问题所在，我从cplusplus.com网站上编译了stod的示例：

  // stod示例
 #include< iostream> // std :: cout 
 #include< string> // std :: string，std :: stod 
 
 int main（）
 {
 std :: string orbits（ 365.24 29.53）; 
 std :: string :: size_type sz; // size_t 
 
的别名double earth = std :: stod（轨道，& sz）； 
 double moon = std :: stod（orbits.substr（sz））； 
 std :: cout<<月亮完成<<（地球/月球）<<每个地球年的轨道。\n; 
返回0； 
} 
  

无法编译，错误为无法解决功能站。如果我删除这些调用，并将地球初始化为0.0，将月亮初始化为1.0 ，它可以编译并正常运行（

我尝试从Ubuntu命令行编译相同的程序，当我包含-std = c ++ 11编译标志时，它可以工作。

 > g ++ -o teststod teststod.cpp -std = c ++ 11 
> teststod 
每个地球年月球完成12.3684个轨道。 
  

我的Linux是最新的，并且已经确定要进行更新。
一个可能的线索，我最初仅在Java目标上安装了Eclipse，但是我在Eclipse中将这些项目创建为具有C / C ++透视图的C ++项目。

参考，这是Eclipse的关于页面返回的内容：

 面向Java开发人员的IDE 
版本：Mars.1版本（4.5 .1）
内部版本号：20150924-1200 
 
 Ubuntu版本：
发行者ID：Ubuntu 
描述：Ubuntu 14.04.5 LTS 
发行：14.04 
代号：trusty 
  

解决方案

返回，我决定重新安装所有内容。回顾了youTube 在Windows上设置Eclipse C的视频之后，我意识到安装Eclipse要支持C，需要执行以下步骤：

• 从 java.oracle.com （完成）


• 下载Eclipse（完成）


• 下载C / C ++编译环境（


• 下载Eclipse CDT软件包（未完成）

就像很多人一样，我以为我可以直接下载Eclipse for C / C ++并使其开箱即用，但是我无法构建任何类似helloWorld的教程。我需要单独下载编译器工具链。

我下载并安装了 cygwin 和Eclipse CDT软件包，但仍然出现错误，因为Eclipse找不到标准的包含文件头或make程序。

此帖子讨论了设置 PATH 。我必须在 Window-> Preferences-> C / C ++-> Build-> Environment <下设置项目构建环境 PATH 变量/ code>并将路径 C：\cygwin64\bin 添加到 PATH 变量中。 / p>



在项目属性下，我必须转到位于 C /下的工具链编辑器 C ++构建并将当前工具链设置为 CygWin GCC 和 Current根据以下 post < CDT Internal Builder 生成器 / a>。

由于我是从头开始的，因此我不得不返回并设置 -std = c ++ 0x 表示< project> Properties-> C / C ++ Build-> Settings-> Dialect'下的项目，然后选择 ISO C ++ 11（-std = c ++ 0x）低于语言标准。

该项目然后成功构建并正确运行。感谢StackEchange上为您提供各种帖子的人。

Elipse cannot build C++ programs on my system if they contains calls to string's function stod(). I am running Ubuntu 14.04 with Eclipse using the C/C++ perspective.

I have included the header, and compiled with the -std=c++11 compile flag and set the compiler from gcc to g++, but it did not work. I also tried using Eclipse's "ISO C++11" dialect setting (which sets the compile flag to -std=c++0x. In all cases, the compiler is unable to see the stod function.

To isolate the problem, I compiled the example from the cplusplus.com website for stod:

// stod example
#include <iostream>   // std::cout
#include <string>     // std::string, std::stod

int main ()
{
  std::string orbits ("365.24 29.53");
  std::string::size_type sz;     // alias of size_t

  double earth = std::stod (orbits,&sz);
  double moon = std::stod (orbits.substr(sz));
  std::cout << "The moon completes " << (earth/moon) << " orbits per Earth year.\n";
  return 0;
}

This fails to compile, with the error "Function stod could not be resolved". If I remove those calls, and initialize earth to 0.0, and moon to 1.0, it compiles and runs fine (with the wrong answer of course).

I tried compiling the same program from the Ubuntu command line and it works when I include the -std=c++11 compile flag.

> g++ -o teststod teststod.cpp -std=c++11
> teststod
The moon completes 12.3684 orbits per Earth year.

My Linux is up to date, and I have done an apt-get update to be sure. One possible clue, I originally installed Eclipse with only the Java target, but I created these projects in Eclipse as C++ projects with C/C++ perspectives.

For reference, here is what Eclipse's About page returns:

IDE for Java Developers
Version: Mars.1 Release (4.5.1)
Build id: 20150924-1200

Ubuntu version:
Distributor ID: Ubuntu
Description:    Ubuntu 14.04.5 LTS
Release:    14.04
Codename:   trusty

解决方案

After taking a step back, I decided to reinstall everything. After reviewing a youTube video on setting up Eclipse C on windows, I realized that installing Eclipse to support C required these steps:

• Downloading Java JDK from java.oracle.com (done)
• Downloading Eclipse (done)
• Downloading a C/C++ compile environment (not done!)
• Downloading Eclipse CDT package (not done)

Like many people, I thought I could simply download Eclipse for C/C++ and have it work out of the box, but I could not build any of the tutorials like helloWorld. I needed to download the compiler toolchain separately.

I downloaded and installed cygwin and the Eclipse CDT package, but I still got errors because Eclipse could not find the standard include file headers, nor the make program.

This post talks about setting the PATH. I had to set the project build environment PATH variable under Window->Preferences->C/C++->Build->Environment and added the path C:\cygwin64\bin to the PATH variable.

Under Project Properties, I had to go to the Tool Chain Editor located under C/C++ Build and set Current Toolchain to CygWin GCC and Current builder to CDT Internal Builder according to this post.

And because I was starting from scratch, I had to go back and set -std=c++0x for the project under <project>Properties->C/C++ Build->Settings->Dialect' and chooseISO C++11 (-std=c++0x)underLanguage Standard`.

The project then built successfully and ran correctly. Thanks for everyone on StackEchange who helped with your various posts.

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