erase [C++ Reference]
Keywords: stl,deque,erase
Date: 2009-08-06T02:03:22-0700

[[erase]]
C++ Reference
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## erase

Syntax:

        #include <deque>
        iterator erase( iterator loc );
        iterator erase( iterator start, iterator end );

The erase() function either deletes the element at location loc, or deletes the elements between start and end (including start but not including end). The return value is the element after the last element erased.

The first version of erase (the version that deletes a single element at location loc) runs in constant time for lists and linear time for vectors, deques, and strings. The multiple-element version of erase always takes linear time.

For example:

       // Create a deque, load it with the first ten characters of the alphabet
       deque<char> alphaDeque;
       for( int i=0; i < 10; i++ ) {
         alphaDeque.push_back( i + 65 );
       }
       int size = alphaDeque.size();
       deque<char>::iterator startIterator;
       deque<char>::iterator tempIterator;
       for( int i=0; i < size; i++ ) {
         startIterator = alphaDeque.begin();
         alphaDeque.erase( startIterator );
         // Display the deque
         for( tempIterator = alphaDeque.begin(); tempIterator != alphaDeque.end (); tempIterator++ ) {
           cout << *tempIterator;
         }
         cout << endl;
       }

That code would display the following output:

       BCDEFGHIJ
       CDEFGHIJ
       DEFGHIJ
       EFGHIJ
       FGHIJ
       GHIJ
       HIJ
       IJ
       J

In the next example, erase() is called with two iterators to delete a range of elements from a deque:

       // create a deque, load it with the first ten characters of the alphabet
       deque<char> alphaDeque;
       for( int i=0; i < 10; i++ ) {
         alphaDeque.push_back( i + 65 );
       }
       // display the complete deque
       for( int i = 0; i < alphaDeque.size(); i++ ) {
         cout << alphaDeque[i];
       }
       cout << endl;

       // use erase to remove all but the first two and last three elements
       // of the deque
       alphaDeque.erase( alphaDeque.begin()+2, alphaDeque.end()-3 );
       // display the modified deque
       for( int i = 0; i < alphaDeque.size(); i++ ) {
         cout << alphaDeque[i];
       }
       cout << endl;

When run, the above code displays:

       ABCDEFGHIJ
       ABHIJ

Related Topics: clear, insert, pop_back, pop_front

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