C ++ template library STL - queue

STL containers are pockets A dream ~
0, the access queue container element

#include <stdio.h>
#include <queue>
using namespace std;

int main(){
	queue<int>q;
	for(int i = 1;i <=5;i++){
		q.push(i);
	}
	printf("%d %d\n",q.front(),q.back());
	return 0;
}

1, commonly used functions
pop

#include <stdio.h>
#include <queue>
using namespace std;

int main(){
	queue<int>q;
	for(int i = 1;i <= 5;i++){
		q.push(i);
	}
	for(int i = 1;i <= 3;i++){
		q.pop();//不能写q.pop(i),因为弹出始终是队列头 
	}
	printf("%d\n",q.front());
	return 0;
}

empty()

#include <stdio.h>
#include <queue>
using namespace std;

int main(){
	queue<int>q;
	if(q.empty() == true){
		printf("Empty\n");
	}
	else{
		printf("Not Empty\n");
	}
	q.push(1);
	if(q.empty() == true){
		printf("Empty\n");
	}
	else{
		printf("Not Empty\n");
	}
	return 0;
} 

size () Returns the number of elements in the queue

#include <stdio.h>
#include <queue>
using namespace std;

int main(){
	queue<int>q;
	for(int i = 1;i <= 5;i++){
		q.push(i);
	}
	printf("%d\n",q.size());
	return 0;
}

Common uses: the realization of breadth-first search, you can not own a queue implemented manually, using a queue
addition, front () and pop () before the function, must be empty () to determine whether the queue is empty