key

    A pointer to the object to be sought in the array. This pointer
    should be of type pointer-to-object and cast to type pointer-to-
    void.

 base

    A pointer to the initial member of the array. This pointer should
    be of type pointer-to-object and cast to type pointer-to-void.

 nmemb

    The number of objects in the array.

 size

    The size of an object, in bytes.

 compar

    A pointer to the comparison function.