initialChar.R

initialChar <- function( 
    txt,                           # Text to parse.
    adm = "[:lower:]",             # Acceptable values for the output.
    err = "Not acceptable value"   # Error message if not in the acceptable values.
    ){
    ###############################################################################
    # Mango Solutions, Chippenham SN14 0SQ 2006
    # initialChar.R Fri Sun Jun 03 20:05:15 BST 2007 @836 /Internet Time/
    #
    # Author: Romain
    ###############################################################################
    # DESCRIPTION: gets the first letter from a character string and "lower case" it
    # KEYWORDS: check, component:support
    ###############################################################################
    
    # Tidy up the input.
    if(missing(txt) || is.null(txt) || length(txt) == 0) 
        ectdStop("no character string to use")
    if(length(txt) > 1)
        ectdWarning("only the first element has been used")
    txt <- as.character( txt[1] )  
    
    # Figure out where is the first letter in that string and extract it.
    re <- regexpr("[[:alpha:]]", txt)
    if(re == -1)
        ectdStop("No character in the string")
    out <- casefold( substring(txt,re,re ) )
    
    # Checks if the output is one of the possibilities given.
    rx <- paste("[", casefold(adm) , "]", sep = "")
    if( out %!~% rx )
        ectdStop( err )
    out
}