Item # of () in ()
(item # of [] in [ v])
Category List
Type Reporter
Introduced in 3.0
The correct title of this article is Item # of () in (). The Scratch Wiki uses this different title because of technical restrictions.

Item Number of () in () is a list block and a reporter block. This block reports the index in a list where an item first appears. If an item appears more than once, it reports the index of the first occurrence of that item. If the item is not in a list, it reports 0. It is one of only two reporter blocks that can be inserted into a boolean input, the other one being the Item () of () (block) block.

Example

when gf clicked
delete all of [list v]
add [a] to [list v]
add [b] to [list v]
add [c] to [list v]
add [b] to [list v]
say (item # of [c] in [list v]) //says 3 since c is the third item in the list
say (item # of [b] in [list v]) //says 2 since the first occurrence of b in the list is in the second position
say (item #  of [d] in [list v]) //says 0 since d is not in the list

Workaround

This can instead be accomplished by looking at each item in a list in order and seeing if any of them equal the item being searched for:

define item # of (search term) in list
set [counter v] to (0)
set [result v] to (0)
repeat (length of [list v])
  change [counter v] by (1)
  if <(item (counter) of [list v])=(search term)> then
    set [result v] to (counter)
    stop [this script v]
  end
end

or

define item # of (string) in list
set [result v] to [0]
if <[list v] contains (string)?> then
repeat until <(item (result) of [list v]) = (string)> 
change [result v] by (1)
end
end

Related Suggestion

Some Scratchers want an operators block that reports the appearance of a string in another.[1] Such a block would look like this:

(letter # of () in ():: operators)

However, it can be worked around by this code:

define letter # of (letter) in (string)
set [counter v] to (0)
set [result v] to (0)
repeat (length of (string))
  change [counter v] by (1)
  if <(letter (counter) of (string))=(letter)> then
    set [result v] to (counter)
    stop [this script v]
  end
end
Note Note: Only works if the length of letter is 1.

See Also

References

  1. codeman1044. (2019-05-18). "letter # of () in () [title]" topic:351646
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