std::find

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

Find value in range

Returns an iterator to the first element in the range [first,last) that compares equal to val. If no such element is found, the function returns last.

The function uses operator== to compare the individual elements to val.

The behavior of this function template is equivalent to:

template<class InputIterator, class T>
  InputIterator find (InputIterator first, InputIterator last, const T& val)
{
  while (first!=last) {
    if (*first==val) return first;
    ++first;
  }
  return last;
}

Parameters

first, last: Input iterators to the initial and final positions in a sequence. The range searched is [first,last), which contains all the elements between first and last, including the element pointed by first but not the element pointed by last.
val: Value to search for in the range.
T shall be a type supporting comparisons with the elements pointed by InputIterator using operator== (with the elements as left-hand side operands, and val as right-hand side).

Return value

An iterator to the first element in the range that compares equal to val.
If no elements match, the function returns last.

Example

// find example
#include <iostream>     // std::cout
#include <algorithm>    // std::find
#include <vector>       // std::vector

int main () {
  // using std::find with array and pointer:
  int myints[] = { 10, 20, 30, 40 };
  int * p;

  p = std::find (myints, myints+4, 30);
  if (p != myints+4)
    std::cout << "Element found in myints: " << *p << '\n';
  else
    std::cout << "Element not found in myints\n";

  // using std::find with vector and iterator:
  std::vector<int> myvector (myints,myints+4);
  std::vector<int>::iterator it;

  it = find (myvector.begin(), myvector.end(), 30);
  if (it != myvector.end())
    std::cout << "Element found in myvector: " << *it << '\n';
  else
    std::cout << "Element not found in myvector\n";

  return 0;
}

Output:

Element found in myints: 30
Element found in myvector: 30

Complexity

Up to linear in the distance between first and last: Compares elements until a match is found.

Data races

Some (or all) of the objects in the range [first,last) are accessed (once at most).

Exceptions

Throws if either an element comparison or an operation on an iterator throws.
Note that invalid arguments cause undefined behavior.