Difference between std::fstream and Boost Iostreams Library

Question

I am a newbie of BOOST library. Today I saw a small code segment, where reading and writing a PGM format image was implemented with Boost Iostreams Library. As I am more familiar with STL, I can easily tell that std::fstream can do the same job. Then my question is, what's the point of using Boost library in such a simple reading and writing PGM image application? Moreover, I was wondering in which situation BOOST Iostreams Library is most needed. Thanks!

Answer 1

From std::fstream reference :

fstream provides an interface to read and write data from files as input/output streams.

From Boost.Iostreams reference :

Boost.Iostreams has three aims:

• To make it easy to create standard C++ streams and stream buffers for accessing new Sources and Sinks.
• To provide a framework for defining Filters and attaching them to standard streams and stream buffers.
• To provide a collection of ready-to-use Filters, Sources and Sinks.