C++ 打字是不相关的——你的编辑应该替你打字。这很好，因为它使代码比到处都有std:：更具可读性，并且比使用std:：whatever的三十行更易于维护在每个文件的顶部。我可以在一行中包含来自std的多个元素吗？例如：使用std:：string，std:：mak

---

打字是不相关的——你的编辑应该替你打字。这很好，因为它使代码比到处都有

std:：

更具可读性，并且比使用std:：whatever的三十行

更易于维护在每个文件的顶部。我可以在一行中包含来自std的多个元素吗？例如：使用std:：string，std:：make_shared；
using namespace std;

#include <iostream>
using namespace std;

...
cout << "Hi" << endl;

#include <iostream>

...
std::cout << "Hi" << std::endl;

std::cout << "I am accessing stdout" << std::endl;

using std::cout;
using std::endl;
cout << "Hello" << endl;
std::cout << "Hello" << std::endl;
using namespace std;

using std::string;

using namespace std;

std::cout << "cout is declared within the namespace std";

using namespace std;
string myString;

std::string myString;

using std::string;
string myString;

using std::cout;

using namespace std;

namespace intutils
{
    int addNumbers(int a, int b)
    {
        return a + b;
    }
}

#include "common1.h"    
int main()
{
    int five = 0;
    five = addNumbers(2, 3); // Will fail to compile since the function is in a different namespace.
    five = intutils::addNumbers(2, 3); // Will compile since you have made explicit which namespace the function is contained within.

    using namespace intutils;
    five = addNumbers(2, 3); // Will compile because the previous line tells the compiler that if in doubt it should check the "intutils" namespace.
}

#include <iostream>
#include <algorithm>

namespace zzz
{
    struct X {};


void swap(zzz::X&, zzz::X&) 
{
    std::cout << "Swapping X\n";
}
}

template <class T>
void dumb_swap(T& a, T& b)
{
    std::cout << "dumb_swap\n";
    std::swap(a, b);
}

template <class T>
void smart_swap(T& a, T& b)
{
    std::cout << "smart_swap\n";
    using std::swap;
    swap(a, b);
}

int main()
{
    zzz::X a, b;
    dumb_swap(a, b);
    smart_swap(a, b);

    int i, j;
    dumb_swap(i, j);
    smart_swap(i, j);
}

//copy numbers larger than 1 from stdin to stdout
remove_copy_if(
    std::istream_iterator<int>(std::cin), std::istream_iterator<int>(),
    std::ostream_iterator<int>(std::cout, "\n"),
    std::bind2nd(std::less_equal<int>(), 0)
);

// cstdio
namespace std
{
  // ...
  int printf(const char* ...);
  // ...
}

// stdio.h
#include <cstdio>
using namespace std;