while loops

When you want to use looping as long as a condition stays true, use the while loop, which is as follows:

a = 10; b = 15 
while a < b 
    # body: process(a) 
    global a += 1 
# prints on consecutive lines: 10 11 12 13 14 

In the body of the loop, something has to change the value of a so that the initial condition becomes false and the loop ends. If the initial condition is false at the start, the body of the while loop is never executed. The global keyword makes a in the current scope refer to the global variable of that name.

If you need to loop over an array while adding or removing elements from the array, use a while loop, as follows:

arr = [1,2,3,4] 
while !isempty(arr) 
    print(pop!(arr), ", ") 

The preceding code ...

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