1. Your array should contain only elements of the same (or some derived) type.
2. There should be a totally order defined on those type of elements.
3. If your array is of one only dimension searching it for the largest and smallest element in a simple loop shouldn't be as difficult. Or did I misunderstand your question?
Before the loop begins, set both the max and min to the value of the first array element. Use a loop and the < or > operator as appropriate, to test each value, and replace the current max or min as required.