Purpose: Original value is origVal, we want to use increase/decrease to update to a specified number
How?
- origValue = origValue + expectedValue
- diff = expectedValue - origValue
- origValue = origValue + diff
Ex. origValue = 54, newValue = 50
- origValue = origValue (54) + expectedValue (50) = 104
- diff = expectedValue (50) - origValue (104) = -54
- origValue = origValue (104) + diff (-54) = 50
沒有留言:
張貼留言