C++ Deque swap() Usage and Example

C++ Deque (Double-ended Queue)

C ++ The Deque swap() function swaps the content of the given deque with another deque of the same type passed as an argument.

Condition:

• The type of the deque must be the same.

• The size of the deque can be unequal.

Syntax

void swap(deque& second);

Parameter

second：This is another deque container whose content will be swapped with the given deque.

Return value

It does not return any value.

Example1

Let's see a simple example

Example

#include <iostream>
#include<deque>
using namespace std;
int main()
{
　　　　deque<string> str={"C is a programming language"};
　　　　deque<string> str1={"java is a programming language"};
　　　　
　　　　str.swap(str1);
　　　　deque<string>::iterator itr=str.begin();
　　　　　deque<string>::iterator itr1=str1.begin();
　　　　cout << "After the swap, the value of str is: " <<*itr;
　　　　cout << '\n';
　　　　　cout << "After the swap, str1The value is: "<<"*itr1;
　　　　return 0;
　}

Output:

After the swap, the value of str is: "java is a programming language"
After the swap, str1The value is: "C is a programming language"

In this example, the swap() function swaps str and str1The content. Now, str contains "java is a programming language", and str1Containing "C is a programming language".

Example2

Let's see a simple example when two deques are of different types.

Example

#include <iostream>
#include<deque>
using namespace std;
int main()
{
　　　　deque<char> c={'m','a','n','g','o'};
　　　　deque<int> s={1　,2,3,4,5};
　　　　c.swap(s);
　　　　return 0;
　　　}

Output:

error: no matching function for call to 'std::deque<char>::swap(std::deque<int>&)'

In this example, the swap() function will cause an error because the types of the two deques are different.

Example3

Let's see a simple example when the sizes are different.

Example

#include <iostream>
#include<deque>
using namespace std;
int main()
{
　　　　deque<int> first={1,2,3,4};
　　　　deque<int> second={10,20,30,40,50};
　　　　deque<int>::iterator itr;
　　　　first.swap(second);
　　　　cout << "The content of the first deque:";
　　　　for(itr=first.begin();itr!=first.end();++itr)
　　　　cout <<*itr << "  ";
　　　　cout << '\n';
　　　　cout << "Content of the second double-ended queue:";
　　　　　for(itr=second.begin();itr!=second.end();++itr)
　　　　cout <<*itr << "  ";
　　　　return 0;
　　　　}

Output:

Content of the first double-ended queue:10　20　30　40　50　
Content of the second double-ended queue:1　2　3　4

In this example, the swap() function exchanges the content of the first double-ended queue to the second double-ended queue.

C++ Deque (Double-ended Queue)