std::vector – Tech Blog of Edward

Declaration

vector<int> v;

// Size of 100 and initialize all to 0
vector<int> v(100, 0)

// Reserve size of 3, to prevent extra complexity for copying
v.reserve(3);

vector<int> v;

// Size of 100 and initialize all to 0

vector<int> v(100, 0)

// Reserve size of 3, to prevent extra complexity for copying

v.reserve(3);

Simple operation

int n;
v.push_back(n);

1 2	int n; v.push_back(n);

Fill with something

fill(v.begin(), v.end(), 101);

1	fill(v.begin(), v.end(), 101);

Combine two vectors

vector<int> head, tail;

head.insert(head.end(), tail.begin(), tail.end());

vector<int> head, tail;

head.insert(head.end(), tail.begin(), tail.end());

In-place solution for creating object

class Coord {
private:
	int x, y;
public:
	Coord(int x, int y)
		: x(x), y(y) {}
};

class Coord {

private:

int x, y;

public:

Coord(int x, int y)

: x(x), y(y) {}

};

Originally, object gets created first in the main stack and then copied to the vector’s memory address

vector<Coord>v;
Coord tmp(1, 2);
v.push_back(tmp);

vector<Coord>v;

Coord tmp(1, 2);

v.push_back(tmp);

In-place object creation can be achieved and save the computing time for copying the object

vector<Coord>v;
v.emplace_back(1, 2); // Pass the parameters of the constructor directly

1 2	vector<Coord>v; v.emplace_back(1, 2); // Pass the parameters of the constructor directly