While std::string stores a resizeable character array, std::vector stores a resizeable array of any type.
std::vector is not a type or class. It is a class template which you will learn more about towards the end of the course. std::vector represents a family of types for the storage and manipulation of a dynamic array. It is found in the <vector> header file. To generate a type from std::vector, std::vector must be instantiated by supplying a type to it's template parameter.
The declaration std::vector<double> v; creates a variable of type std::vector<double>.
Here are some operations supported by a vector for some variable v whose elements are for some type T:
| Expression | Meaning |
|---|---|
| v = v2 | Copies all the elements from vector v2 and assigns them to v |
| v[i] | Accesses the element of v at index i |
| v.front() | Accesses the first element of v |
| v.back() | Accesses the last element of v |
| v.empty() | Returns true if v has zero elements |
| v.size() | Returns the number of elements in v |
| v.clear | Deletes all elements from v |
| v.push_back(x) | Appends an element with value x to v |
| v.pop_back() | Deletes the last element from v |
A vector also supports insert and erase like std::string does, but it requires the use of iterators which you will learn about soon.
A vector cannot be initialized from an initializer list unless your compiler is using C++11 or higher.