C++ Algorithm Library - find() Function

Description

The C++ function std::algorithm::find() finds the first occurrence of the element. It uses operator = for comparison.

Declaration

Following is the declaration for std::algorithm::find() function form std::algorithm header.

C++98

template <class InputIterator, class T>
InputIterator find (InputIterator first, InputIterator last, const T& val);

Parameters

• first − Input iterator to the initial position.

• last − Input iterator to the final position.

• val − Value to compare the elements.

Return value

If element found it returns an iterator pointing to the first occurrence of the element otherwise returns last.

Exceptions

Throws exception if either element comparison or an operation on an iterator throws exception.

Please note that invalid parameters cause undefined behavior.

Time complexity

Linear.

Example

The following example shows the usage of std::algorithm::find() function.

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main(void) {
   int val = 5;
   vector<int> v = {1, 2, 3, 4, 5};

   auto result = find(v.begin(), v.end(), val);

   if (result != end(v))
      cout << "Vector contains element " << val << endl;

   val = 15;

   result = find(v.begin(), v.end(), val);

   if (result == end(v))
      cout << "Vector doesn't contain element " << val << endl;

   return 0;
}

Let us compile and run the above program, this will produce the following result −

Vector contains element 5
Vector doesn't contain element 15