9.3.5. Resizing a Container

With the usual exception of arrays, we can use resize, described in Table 9.9, to make a container larger or smaller. If the current size is greater than the requested size, elements are deleted from the back of the container; if the current size is less than the new size, elements are added to the back of the container:

list<int> ilist(10, 42); // ten ints: each has value 42
ilist.resize(15);     // adds five elements of value 0 to the back of ilist
ilist.resize(25, -1); // adds ten elements of value -1 to the back of ilist
ilist.resize(5);      // erases 20 elements from the back of ilist

Table 9.9. Sequential Container Size Operations

The resize operation takes an optional element-value argument that it uses to initialize any elements that are added to the container. If this argument is absent, added elements are value initialized (§ 3.3.1, p. 98). If the container holds elements of a class type and resize adds elements, we must supply an initializer or the element type must have a default constructor.