# Do Until

Hi guys, I have some spare time today so thought I would spend it on getting better at PS.
I am doing this challenge but I am a little confused with the output of a do/until.

My code.

```\$Minimum = 1
\$Maximum = 100

Do{
\$Target = Read-Host "Please enter a number between \$Minimum - \$Maximum"
}
Until (\$Target -gt "0" -and \$Target -lt "101")
```

I was expecting this to allow any number between 1-100., however, I am only allowed ‘100’ everything else continues in the Do loop.

Can someone explain why this happens? I assume it is to do with the -and operator…
I’m fairly sure that I could do this another way, but I would like to work out why it’s behaving in this way.

You’re comparing strings instead of integers.

```\$Minimum = 1
\$Maximum = 100

Do{
[int]\$Target = Read-Host "Please enter a number between \$Minimum - \$Maximum"
}
Until (\$Target -gt "0" -and \$Target -lt "101")
```

I think Powershell is smart enough to interpret \$target as an int even though this wasn’t explicitly declared [int]\$target.
So the loop should continue until it is true? So if you enter any integer outside the range you keep looping?

Your right and that fixed my problem, but, I still don’t get why 100 worked. Shouldn’t it fail as well due to the same problem, comparing a string to an integer?

It’s comparing 2 strings. I guess it compares them character by character, and “100” is less than “101”.

yes, anything outside of that that isn’t ‘100’ i.e. 0,1,2…99 and 101,102…
at least for all the ones that i tried.

not sure if I am just being dense, but so is ‘99’ but that fails.
Oh wait, I think I get you. Your right, because 1 works as well, i just hadn’t tested it.

Try it on the command line:

```"99" -lt "100"

False
```

I guess in strings if the 9 is greater than the one it’s greater.

\$Minimum = 1
\$Maximum = 100

Do{
[int]\$Target = Read-Host “Please enter a number between \$Minimum - \$Maximum”
}
Until (\$Target -gt “0” -and \$Target -lt “101”)
Please enter a number between 1 - 100: 99

PS H:&gt; \$Target | gm

TypeName: System.Int32

Awesome. Obviously, my issue was not declaring the [int] (Thanks @Andrew). But now I understand the behaviour I was getting where it was comparing each number in 101 individually (thanks @js).

This is what I came up with, is there anything I could have done better?

```\$Minimum = 1
\$Maximum = 100

Do{
Write-Output "Invalid Number Selected"
#Must be read as a integer so that -lt and -gt work as expected, otherwise it compairs string to integer
[int]\$Target = Read-Host "Please enter a number between \$Minimum - \$Maximum"
}
Until (\$Target -gt "0" -and \$Target -lt "101")

# Computer tries to guess number
\$Guess = get-random -Maximum \$Maximum -Minimum \$Minimum
Write-Output "My Guess is \$Guess"

DO {
# User says Higher/Lower
\$Direction = Read-Host "Please Type 'H' for Higher, 'L' for Lower."

If (\$Direction -eq "L"){
Write-Output "I will guess a lower value than \$Guess."
\$Maximum = \$Guess
\$Maximum--
}
ElseIf (\$Direction -eq "H"){
Write-Output "I will guess a higher value than \$Guess."
\$Minimum = \$Guess
\$Minimum++
}
Else {
Write-Output "You have not selected a valid value."
}
\$Guess = get-random -Maximum \$Maximum -Minimum \$Minimum
Write-Output "My new guess is \$Guess"
}
Until (\$Guess -eq \$Target)
\$Guess
Write-Output "I guessed right! 'nWinner, Winner, Chicken Dinner!!"
```

In this section of code:
If (\$Direction -eq “L”){
Write-Output “I will guess a lower value than \$Guess.”
\$Maximum = \$Guess
\$Maximum–
}
ElseIf (\$Direction -eq “H”){
Write-Output “I will guess a higher value than \$Guess.”
\$Minimum = \$Guess
\$Minimum++

if you increment the min or max, don’t that crash your code if you are one off?

yes
Didn’t happen until I tried again today…

Let me see what I can do to fix that.