在VC6的编译器中，这样的代码是没有问题的，因为VC6的编译器为了兼容旧的Microsoft C/C++编译器，没有严格按照C++标准执行，但是从VC7开始，VC的编译器开始遵守C++标准，所以就会出现“变量i没有定义的错误”。解决的方法也很简单，按照Jim Hyslop 和 Herb Sutter的经典对话系列的第四篇中的方法-VC6 compiler, this code is no problem, because VC6 compiler for compatibility with old Microsoft C/C++ compiler, not strictly in accordance with the C++ standard, but the from VC7 start, the VC compiler to comply with C++ standards, so there will be a variable i is not defined error. The solution is also very simple method in accordance with Jim Hyslop and Herb Sutter' s classic dialogue series fourth