1. Vectors

2. Vectors
Vectors are containers of objects of the same type that are stored contiguously in memory.
In the <vector> library.
Syntax:
vector<double> vect(10);
// initialize vector of 10 doubles.

3. Example Vector Usage vector<int> v(10); v.push_back(4);
v.pop_back();
v.push_back(1);
cout << v[0] << v[1];

4. Vector Operations Assume that v is a vector.
- v.front() // return the first element
- v.back() // return the last element
- v[i] // return the element at index i
- v.at(i) // return the element at index i
- v.push_back(x) // add element x to the end, increase size if necessary
- v.pop_back() // remove the element, reduce size by 1

5. Print a Vector void printVec(const vector<int> &vec) {
for (int i=0; i < vec.size(); i++)
cout << vec.at(i) << “ “;
cout << “\n”; }

6. Out of Bounds Errors
Accessing a vector outside of the allocated space leads to undefined behavior.
vector<int> vec;
for(int i=0; i<5; i++)
vec.push_back(i*2+1);
cout << vec.at(5);

7. Size vs. Capacity v.size() is the number of elements in v
v.capacity() is the number of elements that can be stored in v in the space that is currently allocated

8. Insert into a vector
Since a vector is stored contiguously in memory, if we want to insert at a specific position, we need to shift everything that comes after it over 1 position.
void insert(vector<int> &vec, int pos, int x) {
int n = vec.size();
vec.push_back(0);
for (int i = n; i > pos; i--)
vec[i] = vec[i-1];
vec[pos] = x; }