使用与typename类似的用法
//: C05:PrintSeq.cpp {-msc}{-mwcc}
// From "Thinking in C++, Volume 2", by Bruce Eckel & Chuck Allison.
// (c) 1995-2004 MindView, Inc. All Rights Reserved.
// See source code use permissions stated in the file 'License.txt',
// distributed with the code package available at www.MindView.net.
// A print function for Standard C++ sequences.
#include <iostream>
#include <list>
#include <memory>
#include <vector>
using namespace std;
template<class T, template<class U, class = allocator<U> >
class Seq>
void printSeq(Seq<T>& seq) {
for(typename Seq<T>::iterator b = seq.begin();
b != seq.end();)
cout << *b++ << endl;
}
int main() {
// Process a vector
vector<int> v;
v.push_back(1);
v.push_back(2);
printSeq(v);
// Process a list
list<int> lst;
lst.push_back(3);
lst.push_back(4);
printSeq(lst);
getchar();
} ///:~
若没有typename关键字
编译器就会把iterator看作是Seq<T>的一个静态数据成员
这是一个用法错误
输出
1
2
3
4