Vectors :
We have seen about vector declaration and size concepts in this post
Now we can go through furthur properties in vectors.
Erasing an element in vector:
If we use pop_back(), we’ll remove the last element.
v.pop_back();
To remove the first element, we can use erase(). We need to pass the element’s position (iterator position), we want to remove, as an
v.erase(v.begin());
We can also remove the last element using erase.
v.erase(v.begin() + v.size() - 1);
clearing the vector in cpp so that it become empty.
v.clear();
Using the first element in vector.
v.front();
or
v[0];
Using last element in vector.
v.back();
or
v[v.size()-1];
Sorting the vector in cpp:
sort(v.begin(),v.end());
Vector is ascending order after sorting.
To get in descending order the syntax is.
sort(v.begin(), v.end(), greater<int>());
To implement sorting we have to include the header.
#include<algorithm>
Example for sorting of vector:
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main() {
vector<int>v;
v.push_back(10);
v.push_back(7);
v.push_back(20);
v.push_back(100);
v.push_back(35);
int sum=0;
sort(v.begin(),v.end());
for(int i=0;i<v.size();i++)
{
cout<<v[i]<<" ";
}
return 0;
}
#include <vector>
#include <algorithm>
using namespace std;
int main() {
vector<int>v;
v.push_back(10);
v.push_back(7);
v.push_back(20);
v.push_back(100);
v.push_back(35);
int sum=0;
sort(v.begin(),v.end());
for(int i=0;i<v.size();i++)
{
cout<<v[i]<<" ";
}
return 0;
}
output:
7 10 20 35 100
We can also sort up to a index in vector by using:
sort(v.begin()+value,v.end());
example:
In our above program if the sort line be like
sort(v.begin()+2,v.end());
The output order is
10 7 20 35 100
So we have control in which range we have to sort our vector this advantage can be used very much in programs.
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