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iOS Objective-C Basics Practicing with Immersive Examples Immersive Examples Code Challenge

Melvin Amador
Melvin Amador
5,239 Points
Posted by Melvin Amador
Melvin Amador
5,239 Points

While Loop

Hi. I'm trying to complete a challenge on While Loops. My question is: why do I keep receiving an error on the following loop. I'm trying to say that as long as rubies are less than rubyMax then increment the rubies amount by the rubyReward. 

int rubies = 0;
int rubyReward = 7;
int rubyMax = 50;

while (rubies < rubyMax)
{
    rubies = rubyReward++;
}
variable_assignment.mm 
bool levelFinished;

int rubies = 0;
int rubyReward = 7;
int rubyMax = 50;

while (rubies < rubyMax)
{
  rubies = ++rubyReward;
}

2 Answers

Joe Scotto
Joe Scotto
8,282 Points
Joe Scotto
Joe Scotto
8,282 Points 
while (rubies < rubyMax)
{
    rubies = rubyReward + 1
}
Danny Iachini
Danny Iachini
1,437 Points

Unfortunately this snippet would cause an infinite loop with the variables provided in the question. The while condition would start at (0 < 50) (which is true) -- so then you'd set rubies to (7+1). The while condition the next time through would be (8 < 50) (still true) -- but rubyReward hasn't changed, so you would again set rubies to (7+1). The while condition the next time through would be (8 < 50) (and here's the pattern now -- rubies will never change to anything other than 8).

rubies  |  rubyReward  |  rubyMax
0       |  7           |  50
8       |  7           |  50
8       |  7           |  50
. . .
8       |  7           | 50

Instead (as answered below), I think inside your for loop, you want to be setting rubies += rubyReward

Danny Iachini
Danny Iachini
1,437 Points
Danny Iachini
Danny Iachini
1,437 Points

rubyReward++ is a post-increment operator (meaning rubies would equal what rubyReward was before adding 1 to it)

++rubyReward is a pre-increment operator (meaning rubies would equal what rubyReward was after adding 1 to it)

This StackOverflow answer has a really good explanation with examples.

When you asked to then increment the rubies amount by the rubyReward, I believe what you're looking for is actually:

while (rubies < rubyMax)
{
    rubies += rubyReward
}