Monday, October 13, 2008

Alliteration algorithm

A function to determine is a string is an alliteration, for example
" as albert asked Anna, an antelope appeared!" is considered to be one.

private static bool IsAnAlliteration(string subject)
bool result = true;

char lead = default(char);

bool inWord = false;

foreach (char c in subject)
char current = char.ToLower(c);

bool isLetter = char.IsLetter(current);
// lead contains first character in string
// all words should start with lead character
if (lead == default(char) && isLetter)
lead = current;

if (!inWord && isLetter && lead != current)
result = false; // start of new word, but does not start with lead char
else if (!inWord && isLetter && lead == current)
inWord = true; // start of new word starts with lead char
else if (inWord && char.IsWhiteSpace(current))
inWord = false; // end of word found

if (!result)
// did we find at least one word
result &= (lead != default(char));

return result;


Inigo said...

Surely an opportunity for some Linq...

public bool IsAlliterative(String s)
return new Regex("[^\\w+]").Split(s).Where(a => a.Length > 0).All(a => a.ToLower().StartsWith("" + Char.ToLower(s.First())));

fe said...

@Inigo - nice, though I guess that using you could just do it using a Regex with captures..

Linq+RegExp - who needs anything else ;-0