If an if statement gets called and all the conditions are true, do all the else if statements get called also?

Question

like:

if coins > 19 && speedLvl == 1 {
    speedLvl = 2
    coins = coins - 20
}

else if coins > 49 && speedLvl == 2 {
    speedLvl = 3
    coins = coins - 50
            }

else if coins > 99 && speedLvl == 3 {
    speedLvl = 4
    coins = coins - 100
}

If the player has 1000 coins do then speedLvl the go to 4 ?

"If the player has 1000 coins do then speedLvl the go to 4 ?" no, would you like it to? — Alexander, Sep 27 '17 at 15:46
@luchsi Your question it is unclear. Please edit it and add what is the expected results. Looks like you should use a switch statement and you can use fallthrough keyword. You can check this answer to see how it works https://stackoverflow.com/questions/31782316/cant-convert-uicolor-from-hex-colour-string-in-swift/31782490?s=1|3.9465#31782490 — Leo Dabus, Sep 27 '17 at 16:03

Alexander · Accepted Answer · 2017-09-27T15:57:22.427

No, and you can visualize it like this:

if coins > 19 && speedLvl == 1 {
    speedLvl = 2
    coins = coins - 20
}
else {
    if coins > 49 && speedLvl == 2 {
        speedLvl = 3
        coins = coins - 50
    }
    else {
        if coins > 99 && speedLvl == 3 {
            speedLvl = 4
            coins = coins - 100
        }
    }
}

Although this code would be more easily written in Swift 4 as:

switch (speedLvl, coins) {
case (1, 20..<50):
    speedLvl += 1
    coins -= 20

case (2, 50..<100): 
    speedLvl += 1
    coins -= 50 

case (3, 100...):
    speedLvl += 1
    coins -= 100

default: break;
}

or better yet, perhaps:

let levelUpCosts = [0, 20, 50, 100]

let levelUpCost = levelUpCosts[speedLvl]
if levelUpCost < coins {
    coins -= levelUpCost
    speedLvl += 1
}

If you want to multiple level ups to be possible, all in one shot, then you can do something like this:

let levelUpCosts = [0, 20, 50, 100]

var affordedLevelUpsCost = 0
let affordedLevelUps = levelUpCosts.lazy.prefix(while: { cost in
    let newCost = affordedLevelUpsCost + cost
    let canAffordLevelUp = newCost < coins
    if canAffordLevelUp { affordedLevelUpsCost = newCost }
    return canAffordLevelUp
})

speedLvl += affordedLevelUps.count
coins -= affordedLevelUpsCost

Curious, what is the name of this new Swift4 feature: `case (1, 20..<50):` — mfaani, Sep 27 '17 at 16:17
@Honey That's just tuple matching, it's not new to Swift 4. The half range operator `100...` is what's new from Swift 4 — Alexander, Sep 27 '17 at 16:26
Interesting, I just tried that in Swift 3 ie doing `100...` will result in the following error: `'...' is not a postfix unary operator`. Yet in Swift4, it would just work... — mfaani, Sep 27 '17 at 18:23

score 0 · Answer 2 · answered Sep 27 '17 at 15:37

No, the if-else conditions will move on after a successful condition is reached.

So, if coins > 19 && speedLvl == 1 if this condition is true, the rest of the else-if conditions won't even be checked.

If the first if-statement is not true, then it will go to each if-else statement until it reaches a true condition. Once it reaches a true if-else condition, it will not check any remaining if-else conditions.

If you would like each of these conditions to be checked, remove the else and have each as a stand alone if-statement to check each condition individually without any dependency on the other conditions.

If an if statement gets called and all the conditions are true, do all the else if statements get called also?

2 Answers2