关于using std::和using namespace std;
#include<iostream>
#include<vector>
using std::cin;
using std::cout;
using std::endl;
using std::vector;
using std::vector<int>::iterator;
int main()
{
vector<int> container;
for(int i=0; i<=4; i++)
container.push_back(i);
cout<<"Here is what is in the container:\n";
iterator p;
for(p = container.begin(); p != container.end(); p++)
cout<<*p<<" ";
cout<<endl;
cout<<"Setting entries to 0:\n";
for(p = container.begin(); p!=container.end(); p++)
*p=0;
for(p = container.begin(); p != container.end(); p++)
cout<<*p<<" ";
cout<<endl;
char c;
cin>>c;
return 0;
}
error C2885: “std::vector<_Ty>::iterator”: 在非类范围内不是有效的 using 声明 f:\ch8\ch10\ch10\源2.cpp 7 ch10
cpp(17) : error C2065: “iterator”: 未声明的标识符
为什么会有这个错误提示,而把它改成以下代码的时候就可以通过,不都一样吗????
#include<iostream>
#include<vector>
using namespace std;
int main()
{
vector<int> container;
for(int i=0; i<=4; i++)
container.push_back(i);
cout<<"Here is what is in the container:\n";
for(vector<int>::iterator p = container.begin(); p != container.end(); p++)
cout<<*p<<" ";
cout<<endl;
cout<<"Setting entries to 0:\n";
for(vector<int>::iterator p = container.begin(); p!=container.end(); p++)
*p=0;
for(vector<int>::iterator p = container.begin(); p != container.end(); p++)
cout<<*p<<" ";
cout<<endl;
char c;
cin>>c;
return 0;
}
关于using std:: 和 using namespace std;的用法想请大家指点下