c4，configure the debug environment

　　Yesterday I found a tiny C compiler (less than 600 line of C code, containing commits) called "c4" on github and I wanted to know how I can write a compiler in details.

　　During the process, I encounter the following problems:

1> Can not compile c4 on Windows platform, because no "unistd.h" on Windows.

solution: replace the include sentence by the following statements:

　　许多在Linux下开发的C程序都需要头文件unistd.h，但VC中没有个头文件， 
　　所以用VC编译总是报错。把下面的内容保存为unistd.h，可以解决这个问题。

1. 1. 　　/** This file is part of the Mingw32 package.
   2. 　　 *  unistd.h maps     (roughly) to io.h
   3. 　　 */
   4. 　　#ifndef _UNISTD_H
   5. 　　#define _UNISTD_H
   6. 　　#include <io.h>
   7. 　　#include <process.h>
   8. 　　#endif /* _UNISTD_H */

2> IDEs:

First tried Vitual Studio 2013, it was hard for me to get used the VS after some many years‘ leave. I could not find the proper functions to satisfy my needs.

Eclipse: Downloaded the Eclipse-CDT(for C/C++ development). Dowload the minGW project, containing the gcc and other lib file for windows. Configure eclipse, it is not complicated after I configure the BarLearner project from Cristian. Just make the build system right, and adjust the run configuration. But I fould I could not the value of global values and for most pointers, I could only see the address its point to rather than the  content (for example, I wanted to see an array, but got nothing useful for me.) Searching on the Internet, someone said we can see the global values on "Watch" windows. However, I did not think so after trying. I gave it up temporary.

VC6.0: This is a very old platform I had been working on for years. It took me time to install VC 6.0 on Windows 8.1. Here are some useful solution for the installation:

　　“1 改名 MSDEV.EXE改成 MSDEV3.EXE
　　2 兼容模式修改成 winxp sp2 或者sp3
　　3 启动MSDEV3.EXE，如果报错，关闭，立刻再次启动，一般就可以正常启动了，成功启动一次后，以后就可以正常运行了
　　4 取消兼容模式，如果运气好，也可以正常运行了，如果不介意，就一直用兼容模式运行也可以"

After that, I found VC 6.0 can not show line number by default. WTF! I need a plug in to complete this need.

　　1. 如果你的VC安装在C盘，请拷贝文件VC6LineNumberAddin.dll到如下目录： C:\Program Files\Microsoft Visual Studio\Common\MSDev98\AddIns

　　2. 注册

　　双击VC6LineNumberAddin.reg进行注册。

　　3. 启用 

　　打开vc6，菜单栏：Tools -> customize -> Add-ins and Macro Files 选中VC6LineNumber Developer Studio Add-in

　　关闭VC，重启VC即可。

Also, I got a link for setting up vim+GDB environment:

http://easwy.com/blog/archives/advanced-vim-skills-vim-gdb-vimgdb/