为什么设置全局的locale会影响cout输出中文？

[alexdboy]

平台为Windows XP Pro和VC2005。代码如下
/*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
#include <iostream>
#include <string>

using std::cout;
using std::endl;
using std::locale;
using std::string;

int main(int argc, char *argv[])
{
string str = "a严a";
//输出全局和cout的locale名称
cout << locale().name() << endl;
cout << cout.getloc().name() << endl;
cout << "===========================" << endl;
printf(str.c_str());
cout << endl << str << endl;
cout << "===========================" << endl;

//C++方式设置全局locale
locale::global(locale(""));

//输出全局和cout的locale名称
cout << locale().name() << endl;
cout << cout.getloc().name() << endl;

cout << "===========================" << endl;
printf(str.c_str());
cout << endl << str << endl;
return 0;
}
/*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/

输出结果为
/*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
C
C
===========================
a严a
a严a
===========================
Chinese_People's Republic of China.936
C
===========================
a严a
a请按任意键继续. . .
/*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/

程序默认的locale是“C”，这时使用printf和cout都能输出中文。在使用了locale::global(locale(""))把程序的全局的locale改成系统默认的“Chinese_People's Republic of China.936”后，printf还是照样输出中文，但cout却失败了（只输出了a）。这是为什么呢？cout的locale应该是不受全局locale的影响的（通过输出cout.getloc().name()也证实了这一点）。我还试了单独把cout的locale改成系统默认的“Chinese_People's Republic of China.936”，保持全局的locale不变，cout可以正常输出中文。可见“Chinese_People's Republic of China.936”这个locale并不是不合适的。
后来我把工程从dubug改成release，运行后出来的结果就正常了
输出结果
/*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
C
C
===========================
a严a
a严a
===========================
Chinese_People's Republic of China.936
C
===========================
a严a
a严a
请按任意键继续. . .
/*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/

虽然这个问题算是暂时解决了，可心里总是放不下。想请各位大侠给解释一下该问题本质上可能是由什么引起的。谢谢。

[nineforever]

Vista，VS2008，debug输出
C
C
===========================
a严a
a严a
===========================
Chinese (Simplified)_People's Republic of China.936
C
===========================
a严a
a严a

[alexdboy]

也许只是VC2005库的bug吧。多谢楼上的。

[jiangmingfu010]

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