binary_search
Syntax:
#include <algorithm> bool binary_search( iterator start, iterator end, const TYPE& val ); bool binary_search( iterator start, iterator end, const TYPE& val, Comp f );
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.
For example, the following code uses binary_search() to determine if the integers 0-9 are in an array of integers:
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; } }
When run, this code displays the following output:
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
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