error LNK2001: 无法解析的外部符号 __environ

在把一个Linux开源程序，移植到Windows的过程中遇到这个错误。

使用vs2010 编译器。

大致代码如下：

#include <stdlib.h>

……extern char **environ;/* defined in run-time library */

……for (n = 0, p = environ; (*p != (char *)NULL); ++p){

错误原因及解决方法：

When you are using /Md (or variants), the symbols _environ and _wenviron are replaced by function calls. You need to track down the code that uses these (obsolete and deprecated) symbols, and make them use the proper function names. I found lots of people with the same problem as you in google also.


I found some more detail here:


Polling _environ in a Unicode context is meaningless when /MD or /MDd linkage is used. For the CRT DLL, the type (wide or multibyte) of the program is unknown. Only the multibyte type is created because that is the most likely scenario.


If you change the use of the symbol _environ to the wide character version _wenviron, your original code will probably work.