为什么我必须双运行make来完全编译我的程序？ GNU c ++ [英] Why do I have to double run make to fully compile my program? GNU c++

问题描述

在我的学校服务器上，我只是使用gcc和几乎相同的代码每次我

我下载了我的程序以在NetBeans中调试它，并在几个小时/天后。我终于ALMOST一切正常了。

在看到这里和其他网站上的几个帖子后，我看到由于某种原因，我需要使用g ++而不是gcc编译，因为我使用的是MacBook。我真的不明白..但如果我将gcc更改为g ++并在我的makefile中运行这行：

编辑：

  g ++ -c $< -o $ @ -std = c ++ 0x -lstdc ++ 
  

但是如果我删除-std = c ++ 0x并运行make again。一切都很好。

但是如果我运行make clean必须重新做。

当我把程序放回我的学校服务器时，这会混乱吗？或者应该没问题，只要我有一个makefile在不同于我的MacBook上的makefile的服务器上。

有人可以帮助驱逐为什么会发生这种情况，我可以修复它吗？

这是我第一次运行make时的makefile：

 code> OBJECTS = Ammunition.o Armor.o Consumable.o 
 HEADERS = Ammunition.h Armor.h Consumable.h 
 
 all：Jhack 
 
 ％.o：％.cpp $（HEADERS）
 g ++ -c $< -o $ @ -std = c ++ 0x 
 
 Jhack：$（OBJECTS）main.o 
 g ++ -o Jhack $ ^ 
 
 clean：
 rm -f * .o Jhack 
 
运行：Jhack 
 ./Jhack 
  

b $ b

感谢。

解决方案

首先，对于Linux GNU C编译器， gcc 一个C编译器，而 g ++ 是一个C ++编译器。这意味着当你使用gcc进行编译时，所有的错误信息基本上都是我不知道这个奇怪的语法是什么。

你的学校不是使用Linux服务器，或者gcc可能有一个链接到c ++编译器。或者核心make规则正在用g ++替换你的编译器选择。

我不认为在这方面你需要担心。只要记住差异，并且可能用你的makefile中的宏替换gcc和g ++。

至于-std选项，它选择你想要的C ++标准版本编译反对。由于您的一些代码需要2011 C ++标准，您需要使用-std选项指定。如果你看看你的g ++手册页，它应该告诉你支持什么选项。

你可以尝试 -std = c ++ 0x 或 -std = c ++ 11 或 -std = gnu ++ 11 p>

任何一个都应该给你所需要的功能。根据我的搜索，你不需要指定 -std = stdc ++ ，因为我认为默认包括g ++。

Im terrible with understanding what goes on behind the scenes when running programs.

On my schools server, I just use gcc and pretty much the same code every time I need to make a makefile lol.

I downloaded my program to debug it in NetBeans and after hours/days.. I finally ALMOST have everything working.

After looking at a few posts on here and other sites, I saw that for some reason I need to use g++ instead of gcc to compile since I'm using a MacBook. Which I don't really understand.. But if I change gcc to g++ and run this line in my makefile:

Edit:

 g++ -c $< -o $@ -std=c++0x -lstdc++

I get an error. But if I remove "-std=c++0x" and run make again.. Everything is good to go.

But if I run my "make clean" I have to do it over again..

Will this mess everything up when I put the program back on my schools server? Or should it be fine as long as I have a makefile on the server that is different from the makefile on my MacBook?

Can someone help expelling why this is happening and how I could possibly fix it?

Here's my makefile the first time I run make:

OBJECTS = Ammunition.o Armor.o Consumable.o 
HEADERS = Ammunition.h Armor.h Consumable.h 

all: Jhack

%.o: %.cpp $(HEADERS)
    g++ -c $< -o $@ -std=c++0x

Jhack: $(OBJECTS) main.o
    g++ -o Jhack $^

clean:
    rm -f *.o Jhack

run: Jhack
    ./Jhack

Thanks.

解决方案

First, for Linux GNU C compilers, gcc is a C compiler whereas g++ is a C++ compiler. Which means when you compile with gcc, all your error messages are basically saying, "I don't know what all this strange syntax is."

Your school isn't using a Linux server, or "gcc" there may be a link to a c++ compiler. Or the core make rules are replacing your compiler choice with g++.

I don't think there's all that much you need to worry about in this regard. Just remember the difference, and possibly replace gcc and g++ with a macro in your makefile.

As for the -std option, that's choosing which version of the C++ standard you want to compile against. Since some of your code requires 2011 C++ standard, you need to specify that with your -std option. If you look at your g++ man pages, it should tell you what options are supported.

You can try -std=c++0x or -std=c++11 or -std=gnu++11

Any of those should give you the functionality you require. Based on what I've searched for, you don't need to specify -std=stdc++ since i think that's included by g++ by default.

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