The C++ Standard Library is a large and comprehensive collection of classes and functions for fine-grained, low-level programming. Within this library, you will find the following components:
The large set of data structures and algorithms formerly known as the Standard Template Library (STL)
An iostream facility
A locale facility
A templatized string class
A templatized complex class for representing complex numbers
A valarray class optimized for handling numeric arrays
A uniform framework for describing the execution environment, using a template class named numeric_limits and specializations for each fundamental datatype
Memory management features
Extensive support for national character sets
Exception handling features
The STL portion of the C++ Standard Library is not object-oriented. If you are accustomed to the benefits of object-oriented programming, their absence may necessitate some adjustment. Encapsulation of data and functionality in objects is a hallmark of object-oriented programming. In the C++ Standard Library, however, the data structures are separate from the algorithms you use to manipulate them.
This feature can provide a number of advantages, such as smaller source code, and the flexibility of using algorithms with C++ pointers and arrays as well as conventional objects. It can also lead to more efficient coding and faster execution, since it creates a direct, nuts-and-bolts approach to solving problems.
The main disadvantage of using the C++ Standard Library directly is increased risk of error. For example, the library's iterators must not be mismatched or invalidated, and iterators in multithreaded environments should be wrapped before being shared among threads. The templates can cause less precise diagnostics, and code that grows unexpectedly large. Experience with the library and your own compiler will help diminish these problems.