再谈从vc6迁移到vs2005
作为C++编译器，从vc6到vc8最大的调整就是对C++标准的支持更好了。
我发现的几点不同。
a. For 循环的声明
Vc6: for(int i<0;i<100;++i){}; j = i; (ok)
Vc8: for(int i<0;i<100;++i){}; j = i; (illegal)
int i; for(i<0;i<100;++i){}; j = i; (ok)
Vc8中的for循环中变量的有效期仅仅在for 循环的开始与结束期间有效。
b.string实现
Vc6: string s; char *p = s.begin(); (ok)
Vc8: string s; char *p = s.begin(); (illegal)
string s; char *p = const_cast<char *>(s.c_str()); (ok)
在vc6中,string::iterator被定义为char *,但是vc8中不是
c.更严格的typename声明的需要
Vc6:
template<class T>
class Test
{
public:
typedef map<T,T> mymap;
mymap::iterator mymap_iter;
}; (ok)
Vc8:
template<class T>
class Test
{
public:
typedef map<T,T> mymap;
mymap::iterator mymap_iter;
}; (illegal)
typename mymap::iterator mymap_iter;(ok)
vc8更加严格的要求程序员在类型前面加上typename以避免歧义
d.不允许默认的int类型
Vc6: fun() { return 0;} (ok)
Vc8: fun() { return 0;} (illegal)
int fun() { return 0;} (ok)
vc8不支持默认返回int类型
e.typedef必须是public才能被外界访问到
Vc6:
Class Test
{
typedef int iterator;
};
Test::iterator i; (ok)
Vc8:
Class Test
{
typedef int iterator;
};
Test::iterator i; (illegal)
Class Test
{
public:
typedef int iterator;
};
Test::iterator i; (ok)
附录：一些资源（From msdn)
Overviews:
Moving from 6.0 to 7.1:
- ATL/MFC Breaking changes (6.0 to 7.0) (also seen here but the list isn't as long)
- ATL/MFC Breaking changes (7.0 to 7.1)
- Standard c++ Library changes and issues specific to upgrading
- Compiler breaking changes
- In-depth info on increased standards compliance
- Project upgrading
Moving from 7.1 to 8.0:
- Libraries breaking changes
- ATL obsolete topics and deprecated functions with replacements
- MFC obsolete topics
- Compiler breaking changes
- Deprecated compiler options
- Some removed linker options (mentioned here and here)
- Preprocessor changes
