C++ Deque push_front() Usage and Example

C++ Deque (Double-ended Queue)

C ++ The Deque push_front() function inserts a new element at the beginning of the deque container, and the size of the container increases by one.

Syntax

void push_front(value_type val);

Parameter

valTo add a new value at the beginning.

Return value

It does not return any value.

Example1

Let's look at a simple example

Example

#include<iostream>
#include<deque>
using namespace std;
int main()
{
　　　　deque<int> d={200,300,400,500};
　　　　deque<int>::iterator itr;
　　　　d.push_front(100);
　　　　for(itr = d.begin(); itr != d.end();++itr)
　　　　cout <<*itr << "  ";
　　　　return 0;
　　　}

Output:

100　200　300　400　500

In this example, the push_front() function is inserted into the first element2Add new elements before 00, that is100.

Example2

Let's look at a simple example

Example

#include<iostream>
#include<deque>
using namespace std;
int main()
{
　　　　deque<string> d={"is","a","programming","language"};
　　　　deque<string>::iterator itr;
　　　　d.push_front("java");
　　　　for(itr = d.begin(); itr != d.end();++itr)
　　　　cout <<*itr << "  ";
　　　　return 0;
　　}

Output:

java is a programming language

In this example, the push_front() function adds a new string before the first string 'is', that is, 'java'.

C++ Deque (Double-ended Queue)