I recently answered a SO-question about using -lt or -gt with strings. My answer was based on something I've read earlier which said that -lt compares one char from each string at a time until a ASCII-value is not equal to the other. At that point the result (lower/equal/greater) decides. By that logic, "Less" -lt "less" should return True because L has a lower ASCII-byte-value than l, but it doesn't:
[System.Text.Encoding]::ASCII.GetBytes("Less".ToCharArray())
76
101
115
115
[System.Text.Encoding]::ASCII.GetBytes("less".ToCharArray())
108
101
115
115
"Less" -lt "less"
False
It seems that I may have been missing a crucial piece: the test is case-insensitive
#L has a lower ASCII-value than l. PS doesn't care. They're equal
"Less" -le "less"
True
#The last s has a lower ASCII-value than t. PS cares.
"Less" -lt "lest"
True
#T has a lower ASCII-value than t. PS doesn't care
"LesT" -lt "lest"
False
#Again PS doesn't care. They're equal
"LesT" -le "lest"
True
I then tried to test char vs single-character-string:
[int][char]"L"
76
[int][char]"l"
108
#Using string it's case-insensitive. L = l
"L" -lt "l"
False
"L" -le "l"
True
"L" -gt "l"
False
#Using chars it's case-sensitive! L < l
([char]"L") -lt ([char]"l")
True
([char]"L") -gt ([char]"l")
False
For comparison, I tried to use the case-sensitive less-than operator, but it says L > l which is the opposite of what -lt returned for chars.
"L" -clt "l"
False
"l" -clt "L"
True
How does the comparison work, because it clearly isn't by using ASCII-value and why does it behave differently for chars vs. strings?