Capitalize 1st word of an character array

Using regexprep how do I convert this '99this' to this '99This'?

Answer 1

[Walter Roberson]

regexprep(S, '[a-z]', '(??@upper($1))', 'once' )

[Adam Danz]

S = '99this';
regexprep(S, '[a-z]', '(??@upper($1))', 'once' )  % incorrect replacement

ans = '99(??@upper($1))his'

regexprep(S, '[a-z]', '${upper($0)}', 'once' )

ans = '99This'

[Walter Roberson]

Thanks, Adam.

[Nayeb Hasin]

There was a slight problem... incase the input was 'Nayeb' it shows the output 'NAyeb'... to solve the problem this is a slightly edited version. Thanks @Adam Danz & @Walter Roberson

S='NAyeb'

S = 'NAyeb'

regexprep(lower(S), '[a-z]', '${upper($0)}', 'once' )

ans = 'Nayeb'

Answer 2

[Sean de Wolski]

s = "99this"

s = "99this"

firstletter = letterBoundary("start")+lettersPattern(1)

firstletter = pattern
  Matching:

    letterBoundary("start") + lettersPattern(1)

replace(s, firstletter, upper(extract(s, firstletter)))

ans = "99This"

[Nayeb Hasin]

thanks@Sean de Wolski