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.