STL vector<bool>中的swap方法(4)

原文地址:http://www.cplusplus.com/reference/vector/vector-bool/swap/

public member function

<vector>

std::vector<bool>::swap

• C++98
• C++11

swap containers (1)swap elements (2)

void swap (vector& x);

static void swap (reference ref1, reference ref2) noexcept;

Swap containers or elements

The first signature is the same as described invector::swap(seevector::swapfor more info).

第一个swap方法的签名和vector::swap是一样的。

A static signature to swap individual elements (bits) is added onvector<bool>.

另一个静态的swap方法交换个别的元素(bits)被添加到vector<bool>中

Parameters

x

Anothervector<bool>container. Sizes may differ.

另一个vector<bool>容器，大小可能不同。

例子：

<span style="color:#993399;">#include <iostream>
#include <vector>
using namespace std;
int main()
{
	vector<bool> vb={true,false,false,true};
	vector<bool> vb2{false,true};
	cout<<"vb =";
	for(bool b:vb){
		cout<<b<<" ";
	}
	cout<<endl;
	cout<<"vb2=";
	for(bool b:vb2){
		cout<<b<<" ";
	}
	cout<<endl;
	cout<<"after swap:"<<endl;
	</span><span style="color:#ff0000;">vb.swap(vb2);</span><span style="color:#993399;">
	cout<<"vb =";
	for(bool b:vb){
		cout<<b<<" ";
	}
	cout<<endl;
	cout<<"vb2=";
	for(bool b:vb2){
		cout<<b<<" ";
	}
	cout<<endl;


}</span>

结果截图：

ref1, ref2

References to elements.

referenceis a member type that accesses individual elements while providing an interface that simulates a reference tobool(seereferencefor more info).

指向元素的引用。

引用是一个成员类型，使用一个接口来模仿引用来访问单个的bool元素。

例子：

#include <iostream>
#include <vector>
using namespace std;
int main()
{
	vector<bool> vb={true,true,false,false};
	cout<<"vb =";
	for(bool b:vb){
		cout<<b<<" ";
	}
	cout<<endl;
	vb.swap(vb.front(),vb.back());
	cout<<"after swap(vb.front(),vb.back())"<<endl;
	cout<<"vb =";
	for(bool b:vb){
		cout<<b<<" ";
	}
	cout<<endl;
	vb.swap(vb[0],vb[1]);
	cout<<"after swap(vb[0],vb[1]])"<<endl;
	cout<<"vb =";
	for(bool b:vb){
		cout<<b<<" ";
	}
	cout<<endl;


}

结果截图：

Return value

none

Example

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

// vector<bool>::swap #include <iostream> #include <vector> int main () { std::vector<bool> foo; std::vector<bool> bar; foo.push_back(false); foo.push_back(true); foo.push_back(false); bar.push_back(true); bar.push_back(false); foo.swap (foo[0], foo[1]); bar.swap (bar.front(), bar.back()); foo.swap(bar); std::cout << std::boolalpha; std::cout << "foo contains:"; for (unsigned i=0; i<foo.size(); i++) std::cout << ' ' << foo[i]; std::cout << "\nbar contains:"; for (unsigned i=0; i<bar.size(); i++) std::cout << ' ' << bar[i]; std::cout << '\n'; return 0; }

Edit & Run

Output:

foo contains: false true
bar contains: true false false

Complexity

Constant.

Data races

For(1), both containers are modified.

在（1）中，所有的容器都被修改。

For(2), elements are modified: inboolvectors there are no guarantees on whether concurrently accessing other elements is safe.

在（2）中，元素被修改。在bool版本的vector中不保证同时访问他们的元素是否是安全的。

Exception safety

For(1), seevector::swap.

For(2), it never throws exceptions (no-throw guarantee).

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2014-8-20

于GDUT