为什么g ++找不到iostream.h？ [英] Why can't g++ find iostream.h?

问题描述

我试图理解如何从命令行使用g ++和（最终）Clang在Ubuntu上编译C ++程序。

我发现了一个网页，解释MakeFiles我按照他们的指示。 http://mrbook.org/tutorials/make/

我将这四个示例文件下载到自己的目录中。

• main.cpp


• hello.cpp


• factorial.cpp


• functions.h

然后我继续前进，并举例说明如何手动编译没有MakeFile。

  g ++ main.cpp hello.cpp factorial .cpp -o hello 
  

当我从上面运行命令时，从g ++收到以下错误：

  main.cpp：1：22：fatal错误：iostream.h：没有这样的文件或目录
编译终止。 
 hello.cpp：1：22：fatal错误：iostream.h：没有这样的文件或目录
编译终止。 
 

我唯一的编写c ++的经验是使用一个IDE，如VS C ++ Express或CodeBlocks。是不是编译器应该知道iostream.h是什么，在哪里找到它？

如何摆脱这个错误，所以程序willl编译？ p>

感谢您的帮助。

解决方案

在ISO标准化C ++语言之前，头文件名为< iostream。 h> ，但是当C ++ 98标准发布时，它被重命名为< iostream> c> .h ）。更改代码以使用 #include< iostream> ，而应该编译。

使用命名空间std; 语句为每个源文件添加一个（或前缀每个对iostream函数/对象的引用 std :: specifier），因为命名空间在预标准化的C ++中不存在。 C ++ 98将标准库函数和对象放在 std 命名空间内。

I'm trying to understand how to compile C++ programs from the command line using g++ and (eventually) Clang on Ubuntu.

I found a webpage which explains MakeFiles and I am following their directions. http://mrbook.org/tutorials/make/

I downloaded the four example files into their own directory.

• main.cpp
• hello.cpp
• factorial.cpp
• functions.h

I then went ahead and ran their example of how to manually compile without a MakeFile.

g++ main.cpp hello.cpp factorial.cpp -o hello

When I ran the command from above, I received the following error from g++:

main.cpp:1:22: fatal error: iostream.h: No such file or directory
compilation terminated.
hello.cpp:1:22: fatal error: iostream.h: No such file or directory
compilation terminated.

My only experience with writing c++ is using an IDE such as VS C++ Express or CodeBlocks. Isn't the compiler supposed to know what iostream.h is and where to find it?

How do I get rid of this error so the program willl compile?

Thanks for any help.

解决方案

Before the C++ language was standardized by the ISO, the header file was named <iostream.h>, but when the C++98 standard was released, it was renamed to just <iostream> (without the .h). Change the code to use #include <iostream> instead and it should compile.

You'll also need to add a using namespace std; statement to each source file (or prefix each reference to an iostream function/object with a std:: specifier), since namespaces did not exist in the pre-standardized C++. C++98 put the standard library functions and objects inside the std namespace.

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