Weighted random selection from array

Question

I would like to randomly select one element from an array, but each element has a known probability of selection.

All chances together (within the array) sums to 1.<

Answer 1

The algorithm is straight forward

rand_no = rand(0,1)
for each element in array 
     if(rand_num < element.probablity)
          select and break
     rand_num = rand_num - element.probability