stringhe - i primi 4 caratteri da destra o sinistra

[saltodifondi]

ciao, c'è modo per prelevare da una stringa i primi n caratteri partendo da destra?

ad esempio

stringR("dasdsakjhdaskpincopallo",4) mi restituisce "allo"

stringL("ciaosakjhdaskpincopallo",4) mi restituisce "ciao"

[floyd]

var s = "dasdsakjhdaskpincopallo";
var right = s.substring(s.length-4);

[pietro09]

trovate in rete il secolo scorso

/*------------------------------------------------------------------------
//
-------------------------------------------------------------------------*/
function Right(str, n)
        /***
                IN: str - the string we are RIGHTing
                    n - the number of characters we want to return

                RETVAL: n characters from the right side of the string
        ***/
        {
                
                
                if (n <= 0)     // Invalid bound, return blank string
                   return "";
                else if (n > String(str).length)   // Invalid bound, return
                   return str;                     // entire string
                else { // Valid bound, return appropriate substring
                   var iLen = String(str).length;
                   return String(str).substring(iLen, iLen - n);
                }
        }



/*------------------------------------------------------------------------
//
-------------------------------------------------------------------------*/
function Left(str, n)
        /***
                IN: str - the string we are LEFTing
                    n - the number of characters we want to return

                RETVAL: n characters from the left side of the string
        ***/
        {
                if (n <= 0)     // Invalid bound, return blank string
                        return "";
                else if (n > String(str).length)   // Invalid bound, return
                        return str;                // entire string
                else // Valid bound, return appropriate substring
                        return String(str).substring(0,n);
        }


/*------------------------------------------------------------------------
//
-------------------------------------------------------------------------*/
function Len(str)
        /***
                IN: str - the string whose length we are interested in

                RETVAL: The number of characters in the string
        ***/
{  return String(str).length;  }



/*------------------------------------------------------------------------
//
-------------------------------------------------------------------------*/
function Mid(str, start, len)
/***
        IN: str - the string we are LEFTing
            start - our string's starting position (0 based!!)
            len - how many characters from start we want to get

        RETVAL: The substring from start to start+len
***/
{
        // Make sure start and len are within proper bounds
        if(len == null)
        {
			return String(str).substr(start);
        }
        else
			return String(str).substr(start, len);
			
}

/*-------------------------------------------------------------------------
// Keep in mind that strings in JavaScript are zero-based, so if you ask
// for Mid("Hello",1,1), you will get "e", not "H".  To get "H", you would
// simply type in Mid("Hello",0,1)

// You can alter the above function so that the string is one-based.  Just
// check to make sure start is not <= 0, alter the iEnd = start + len to
// iEnd = (start - 1) + len, and in your final return statement, just
// return ...substring(start-1,iEnd)
--------------------------------------------------------------------------*/

function InStr(strSearch, charSearchFor)
/*
InStr(strSearch, charSearchFor) : Returns the first location a substring (SearchForStr)
                           was found in the string str.  (If the character is not
                           found, -1 is returned.)
                           
Requires use of:
	Mid function
	Len function
*/
{
	for (i=0; i < Len(strSearch); i++)
	{
	    if (charSearchFor == Mid(strSearch, i, 1))
	    {
			return i;
	    }
	}
	return -1;
}