proc cipherVowel {word} {
        set vowels aeiou
        set i [expr {round(rand() * ([string length $vowels] - 1))}]
        set misspelling $word
        foreach l [split $vowels ""] {
                set j [string first $l $word]
                if {$j > -1} {
                        return [string replace $word $j $j [string index $vowels $i]]
                }
                
        }
        return $misspelling
}

proc skip {word} {
        set i [expr {round(rand() * ([string length $word] -1))}]
        return [string replace $word $i $i ""]
}

proc double {word} {
        set i [expr {round(rand() * ([string length $word] -1))}]
        return [string replace $word $i $i [string index $word $i][string index $word $i]]
}

proc reverse {word} {
        set i [expr {round(rand() * ([string length $word] -1))}]
        if { $i == [string length $word] -1} {
                set i [expr [string length $word] -2]
        }
        set j [string index $word [expr $i + 1]]
        set k [string index $word [expr $i]]
        set misspelling [string replace $word $i $i $j]
        return [string replace $misspelling [expr $i + 1] [expr $i + 1] $k]
}

proc skipSpace {word} {
        set i [string first " " $word]
        if { $i > -1} {
                return [string replace $word $i $i ""]
        } else {
                return $word
        }
}

proc insert {word} {
        set letters abcdefghijklmnopqrstuvwxyz
        set i [expr {round(rand() * ([string length $letters] - 1))}]
        set j [expr {round(rand() * ([string length $word] - 1))}]
        return [string replace $word $j $j [string index $word $j][string index $letters $i]]
}


lappend data "this is a test."
lappend data "fall"
lappend data "summer"
lappend data "spring"
lappend data "winter"

puts "correct|incorrect"

foreach word $data {
        puts "$word|[cipherVowel $word]"
        puts "$word|[skip $word]"
        puts "$word|[reverse $word]"
        puts "$word|[skipSpace $word]"
        puts "$word|[insert $word]"
}