Finds an element in the queue array, either by comparing every element with func or by looking up data if no compare function func is provided, and returning the index of the found element.
comparison function, or NULL to find data by value
data for comparison function
Index of the found element or -1 if nothing was found.
1.2
Finds an element in the queue array, either by comparing every element with func or by looking up data if no compare function func is provided, and returning the index of the found element.