C++ Primer, Fifth Edition

Members to Manage Capacity

The vector and string types provide members, described in Table 9.10, that let us interact with the memory-allocation part of the implementation. The capacity operation tells us how many elements the container can hold before it must allocate more space. The reserve operation lets us tell the container how many elements it should be prepared to hold.

Table 9.10. Container Size Management

Note

reserve does not change the number of elements in the container; it affects only how much memory the vector preallocates.