=====binary_search=====
Syntax:

<code>
    #include <algorithm>
    bool binary_search( forward_iterator start, forward_iterator end, const TYPE& val );
    bool binary_search( forward_iterator start, forward_iterator end, const TYPE& val, Comp f );
</code>

The binary_search() function searches from ''start'' to ''end'' for ''val''. The elements
between ''start'' and ''end'' that are searched should be in ascending order as defined
by the < operator. Note that a binary search will not work unless the elements
being searched are in order.

If ''val'' is found, binary_search() returns true, otherwise false.
If the function ''f'' is specified, then it is used to compare elements.

binary_search() runs in [[/complexity|logarithmic time]].

For example, the following code uses binary_search() to determine if the
integers 0-9 are in an array of integers:

<code>
   int nums[] = { -242, -1, 0, 5, 8, 9, 11 };
   int start = 0;
   int end = 7;

   for( int i = 0; i < 10; i++ ) {
     if( binary_search( nums+start, nums+end, i ) ) {
       cout << "nums[] contains " << i << endl;
     } else {
       cout << "nums[] DOES NOT contain " << i << endl;
     }
   }
</code>

When run, this code displays the following output:

<code terminal>
   nums[] contains 0
   nums[] DOES NOT contain 1
   nums[] DOES NOT contain 2
   nums[] DOES NOT contain 3
   nums[] DOES NOT contain 4
   nums[] contains 5
   nums[] DOES NOT contain 6
   nums[] DOES NOT contain 7
   nums[] contains 8
   nums[] contains 9
</code>

Related Topics: [[equal_range]], [[lower_bound]], [[partial_sort]], [[partial_sort_copy]], [[sort]], [[stable_sort]], [[upper_bound]]