2. Introduction to the Standard C++ Library

2.1 Introduction

Every C++ programmer has probably, at one time or another, written a linked list or set, searching and sorting routines. Most likely, the programmer has re-invented the wheel for every new user-defined data type. Design changes are not easy to implement in such cases. Maintaining such code is not very easy, either.

If the common programming components were part of the C++ language, programmers would not need to "re-invent the wheel."

Finally, the C++ language provides you with general purpose components for common programming tasks through the Standard C++ Library. The Standard C++ Library provides powerful and flexible containers, programmable algorithms, and other components that are efficient and extensible.

The facilities provided by the Standard C++ Library are as follows:

• Language support: Provides common type definitions used throughout the library such as characteristics of predefined types, functions supporting start and termination of C++ programs, support for dynamic memory allocation, support for dynamic type identification, support for exception processing, and other run-time support.
• Diagnostics: Includes components for reporting several kinds of exceptional conditions, components for documenting program assertions, and a global variable for error number codes.
• General utilities: Includes components used in other elements of the Standard C++ Library. These components may also be used by any C++ programs. This category also includes components used by the Standard Template Library (STL) and function objects, dynamic memory management utilities, and date/time utilities. This category also includes memory management components from the C library.
• Strings: Includes components for manipulating sequences of characters, where characters may be of type char , w_char , or of a type defined in a C++ program. The library provides a class template, basic_string , that defines the basic properties of strings. The string and wstring types are predefined template instantiations provided by the library.
• Localization: Includes internationalization support for character classification and string collation; numeric, monetary, and date/time formatting and parsing; and message retrieval.
• The Standard Template Library (STL): Provides a C++ program access to the most widely used algorithms and data structures. STL headers can be grouped into three major organizing concepts: containers, iterators, and algorithms. Containers are template classes that provide powerful and flexible ways to organize data: for example, vectors, lists, sets and maps. Iterators are the glue that pastes together algorithms and containers. STL provides a large set of programmable algorithms to handle sorting, searching, and other common tasks.
• Numerics: Includes components to perform seminumerical operations and components for complex number types, numeric arrays, generalized numeric algorithms, and facilities included from the ISO C library.
• Input/output: Includes components for forward declarations of iostreams, predefined iostream objects, base iostream classes, stream buffering, stream formatting and manipulators, string streams, and file streams.

The Standard C++ Library also incorporates the Standard C Library.

2.2 Using the Standard C++ Libraries in Visual C++ 4.2

Microsoft® Visual C++® version 4.2 provides the Standard C++ Library facilities through included files and associated static and dynamic libraries.

A C++ program can use the different components of the Standard C++ Library by including the required header and linking with the appropriate static or dynamic library.

Tables 1 and 2 list all the Standard C++ Library headers and the associated static and dynamic libraries provided by Visual C++ 4.2.

Note: The Standard C++ Library headers do not have an “.h” extension. This is in accordance with the latest C++ working papers.

Visual C++ 4.2 includes the following static and dynamic libraries (in addition to the Microsoft Class Library [MFC]):

• Basic C run-time library
• Standard C++ Library from Plum Hall
• Old iostream library

Note: With Visual C++ 4.2, the iostream support has been pulled out of the C run-time library and exists as an independent entity. Now Visual C++ has the following libraries:

Case 1. Consider the following sample C++ program where test.cpp uses the Standard C++ Library iostream to print "Hello World".

// test.cpp
#include <iostream>
void main() {
    cout << "Hello World" << endl ;
}

In Case 1, test.cpp used the Standard C++ Library input/output component to print "Hello World." The program just includes the Standard C++ Library header <iostream>. When compiling the program, specify a run-time library option: /ML[d],/MT[d], or /MD[d]. The program will then link with a basic run-time library (for example, LIBC.LIB with the /ML option) and a Standard C++ Library (for example, LIBCP.LIB with the /ML option). The /GX option enables exception handling. Exception handling must be enabled for any programs that use the Standard C++ Library.

It is important to remember that starting with Visual C++ 4.2, a C++ program, depending on the run-time library compiler option specified (/ML[d],/MT[d], or /MD[d]), will always link with one Basic C run-time library and, depending on headers included, will link with either a Standard C++ Library (as in the case 1), an old iostream library (as in Case 3), or neither (as in Case 2).

Case 2. Consider the following sample program:

// test.cpp void
main()
{
}

Case 3. Consider the following sample program:

// test.cpp
#include <iostream.h>
void main()
{
}