`While`¶

While[test, body] loop.

$ wo 'i = 0; While[i < 5, i++]; i'
5

The body runs only while the test is True. A test that gives anything else — a number, an unassigned symbol — ends the loop without a message.

$ wo 'i = 0; While[i, i++]; i'
0

$ wo 'While[q, 1]'
Null

While¶