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Stream iterators

2017-05-21 17:05:51

• A stream iterator is a standard Template library in STL, a class template that can be used with any function that accepts a corresponding iterator after it is instantiated (you can think of a stream as a container, store the data in a contiguous buffer, have the function of an iterator, and a similar use).
• Both Istream_iterator and ostream_iterator are in the definition of the <iterator> header file.
• Any type that provides an input operator (>>) and an output operator (<<) can create Istream_iterator objects and Ostream_iterator objects, which overload both functions on their own classes:istream& Operator >> (IStream &is, &myclass c); and ostream& operator << (ostream &os, const &myclass c);

The ostream_iterator is an output stream iterator and also a class template. To define an output stream iterator, you must specify the type of the output object. The constructor for this class has two parameters: the Ostream object that the output iterator points to and a string value that represents the delimiter between the output objects. As a result, you can create an iterator object (that is, class template instantiation) as follows:

• Ostream_iterator<int> (cout, "/n");--for direct use of output stream iterators
• Ostream_iterator<int> Out_iterator (cout, "/n");--Use the pointer out_iterator to

The istream_iterator is an input stream iterator. To define an output stream iterator, you must specify the type of the output object. The constructor for this class has only one argument: The IStream object that the input iterator points to. Instantiate an input stream iterator:

• istream_iterator<int> (CIN);--Direct use
  
• istream_iterator<int> in_iterator (CIN);--Using the pointer name

 Note: When the input iterator parameter is empty (ref.: http://blog.csdn.net/fdl19881/article/details/6685744)

• Use Copy (istream_iterator<int> (CIN),istream_iterator<int> (), Back_inserter (Ivec)), add input to the end of the container in turn , and ends with a file terminator or non-int type value.
• As can be seen by the following program, the iterator automatically adds 1 after each dereference of the output iterator.

1#include <iostream>2#include <iterator>3 using namespacestd;4 5 voidMain ()6 {7ostream_iterator<int> out(cout,"  ");8* out=1;9* out=2;Ten      out; One}

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