Find if all letters in a string are unique

Question

I need to know if all letters in a string are unique. For a string to be unique, a letter can only appear once. If all letters in a string are distinct, the string is unique. If one letter appears multiple times, the string is not unique. ``` "Cwm fjord veg balks nth pyx quiz." # => All 26 letters are used only once. This is unique "This is a string" # => Not unique, i and s are used more than once "two" # => unique, each letter is shown only once ``` I tried writing a function that determines whether or not a string is unique. ``` def unique_characters(string) for i in ('a'..'z') if string.count(i) > 1 puts "This string is unique" else puts "This string is not unique" end end unique_characters("String") ``` I receive the output ``` "This string is unique" 26 times. ``` Edit: I would like to humbly apologize for including an incorrect example in my OP. I did some research, trying to find pangrams, and assumed that they would only contain 26 letters. I would also like to thank you guys…

Accepted Answer

```
s = "The quick brown fox jumps over the lazy dog."
.downcase
("a".."z").all?{|c| s.count(c) <= 1}
# => false
```

Another way to do it is:

```
s = "The quick brown fox jumps over the lazy dog."
(s.downcase !~ /([a-z]).*\1/)
# => false
```

Find if all letters in a string are unique

Solution

Problem