Vectors and Arrays

Vector Subscripts

You can find the size vector by calling the size function.

for(i = 0; i < v.size(); i++)
   do something with v[i];

Using size is actually better than using a magic number (see Quality Tip 2.3).
The function push_back allows you to start out with an empty vector and grow the vector whenever another element is added.
```
vector<double> salaries;
. . . 
double s;
cin >> s;
. . .
salaries.push_back(s);
```
The push_back command resizes the vector by adding one element to its end.
If you already know how many elements you need in a vector, you should specify that size when you define it.
Another member function, pop_back, removes the last element of a vector, shrinking its size by one.
```
salaries.pop_back(); /* Now salaries has size 9 */
```
The standard defines many more useful functions for vectors; in this book, we only use push_back and pop_back.