QUEUE
THEORY
You have seen queue at many places. The data structure queue is also similar to this. FIRST IN FIRST OUT – the one ehich comes first leaves first.. main methode in it
- ENQUEUE adds 1 element to QUEUE at last
- DEQUEUE deletes 1 element from QUEUE from front
- SHOW_FRONT to return the first element of QUEUE without rempving it
IMPLEMENTATION USING C++ STL
HEADER FILE
#include<queue>
if You use #include<bits/stdc++> then the above one is not needed
initiating
In your function where you want to use you want to do like
void myfun(){
queue <int> Q;
}
Here Q is a the object of type queue we will use this Q in further.
check for Empty ness
Q.empty()
if Queue is empty this returns True else False
ENQUEUE
to enque we want to push it
Q.push(5);
DEQUEUE
to dequeue we want to pop
Q.pop();
but before this we want to check wether QUEUE is empty or not. if Empty we cannot pop so the code is
if(!Q.empty())
Q.pop();
we cant do like this
P=Q.pop();
this gives a error
SHOW_FRONT
the front method returns a referance to the first element
if(!Q.empty())
std::cout<<Q.front();
dont forget to check the emptiness of QUEUE
These are the basic methods in queue but stl offers even more they are
show_back
to acces the last inserted element
cout<<Q.back();
here I neglected but check for emptiness always..
size
Q.size returns the size of QUEUE