cppreference.com > C++ Algorithms > find_first_of find_first_of Syntax:
      #include <algorithm>
      iterator find_first_of( iterator start, iterator end, iterator find_start, iterator find_end );
      iterator find_first_of( iterator start, iterator end, iterator find_start, iterator find_end, BinPred bp );
The find_first_of() function searches for the first occurence of any element between find_start and find_end. The data that are searched are those between start and end. If any element between find_start and find_end is found, an iterator pointing to that element is returned. Otherwise, an iterator pointing to end is returned. For example, the following code searches for a 9, 4, or 7 in an array of integers:
     int nums[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
     int* result;
     int start = 0;
     int end = 10;

     int targets[] = { 9, 4, 7 };
     result = find_first_of( nums + start, nums + end, targets + 0, targets + 2 );
     if( *result == nums[end] ) {
       cout << "Did not find any of { 9, 4, 7 }" << endl;
     } else {
       cout << "Found a matching target: " << *result << endl;
     }
Related topics: adjacent_find find find_end find_if (Standard C String and Character) strpbrk