function checkString(object, errmsg) {
    object.value = trim(object.value);
    
    if ( object.value == "" ) {
        alert(errmsg);
        object.style.backgroundColor = "darkred";
        object.style.color = "white";
        object.focus();
        return true;
    } else {
        object.style.backgroundColor = "white";
        object.style.color = "black";
        return false;
    }
}
    
function checkInteger(object, errmsg) {
    object.value = trim(object.value);
    
    if ( object.value == "" ) {
        alert(errmsg);
        object.style.backgroundColor = "darkred";
        object.style.color = "white";
        object.focus();
        return true;
    } else if ( !isInteger(object.value) ) {
        alert(errmsg);
        object.style.backgroundColor = "darkred";
        object.style.color = "white";
        object.focus();
        return true;
    } else {
        object.style.backgroundColor = "white";
        object.style.color = "black";
        return false;
    }
}

function checkFloat(object, errmsg) {
    object.value = trim(object.value);
    
    if ( object.value == "" ) {
        alert(errmsg);
        object.style.backgroundColor = "darkred";
        object.style.color = "white";
        object.focus();
        return true;
    } else if ( !isFloat(object.value) ) {
        alert(errmsg);
        object.style.backgroundColor = "darkred";
        object.style.color = "white";
        object.focus();
        return true;
    } else {
        object.style.backgroundColor = "white";
        object.style.color = "black";
        return false;
    }
}
        

// Removes leading and trailing spaces from the passed string. Also removes
// consecutive spaces and replaces it with one space. If something besides
// a string is passed in (null, custom object, etc.) then return the input.
function trim(inputString) {
    if (typeof inputString != "string") { return inputString; }
    var retValue = inputString;
    var ch = retValue.substring(0, 1);
    while (ch == " ") { // Check for spaces at the beginning of the string
       retValue = retValue.substring(1, retValue.length);
       ch = retValue.substring(0, 1);
    }
    ch = retValue.substring(retValue.length-1, retValue.length);
    while (ch == " ") { // Check for spaces at the end of the string
       retValue = retValue.substring(0, retValue.length-1);
       ch = retValue.substring(retValue.length-1, retValue.length);
    }
    while (retValue.indexOf("  ") != -1) { // Note that there are two spaces in the string - look for multiple spaces within the string
       retValue = retValue.substring(0, retValue.indexOf("  ")) + retValue.substring(retValue.indexOf("  ")+1, retValue.length); // Again, there are two spaces in each of the strings
    }
    return retValue; // Return the trimmed string back to the user
}

 // Declaring valid date character, minimum year and maximum year
 var dtCh= "/";
 var minYear=1900;
 var maxYear=2100;
 
 function isInteger(s){
 	var i;
     for (i = 0; i < s.length; i++){   
         // Check that current character is number.
         var c = s.charAt(i);
         if (((c < "0") || (c > "9"))) return false;
     }
     // All characters are numbers.
     return true;
 }
 
 function isFloat(s){
    var i;
    var dec = 0;
    for (i = 0; i < s.length; i++){   
        var c = s.charAt(i);
        if ( c==',' ) {
            if ( dec==0 ) {
                dec = 1;
           } else {
               return false;
           }
        } else if ( (c < "0") || (c > "9") ) {
            return false;
        }

    }
    return true;
 }
 
 function stripCharsInBag(s, bag){
 	var i;
     var returnString = "";
     // Search through string's characters one by one.
     // If character is not in bag, append to returnString.
     for (i = 0; i < s.length; i++){   
         var c = s.charAt(i);
         if (bag.indexOf(c) == -1) returnString += c;
     }
     return returnString;
 }
 
 function daysInFebruary (year){
 	// February has 29 days in any year evenly divisible by four,
     // EXCEPT for centurial years which are not also divisible by 400.
     return (((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28 );
 }
 
 function DaysArray(n) {
 	for (var i = 1; i <= n; i++) {
 		this[i] = 31
 		if (i==4 || i==6 || i==9 || i==11) {this[i] = 30}
 		if (i==2) {this[i] = 29}
    } 
    return this
 }
 
 function isDate(dtStr){
 	var daysInMonth = DaysArray(12)
 	var pos1=dtStr.indexOf(dtCh)
 	var pos2=dtStr.indexOf(dtCh,pos1+1)
 	var strDay=dtStr.substring(0,pos1)
 	var strMonth=dtStr.substring(pos1+1,pos2)
 	var strYear=dtStr.substring(pos2+1)
 	strYr=strYear
 	if (strDay.charAt(0)=="0" && strDay.length>1) strDay=strDay.substring(1)
 	if (strMonth.charAt(0)=="0" && strMonth.length>1) strMonth=strMonth.substring(1)
 	for (var i = 1; i <= 3; i++) {
 		if (strYr.charAt(0)=="0" && strYr.length>1) strYr=strYr.substring(1)
 	}
 	month=parseInt(strMonth)
 	day=parseInt(strDay)
 	year=parseInt(strYr)
 	if (pos1==-1 || pos2==-1){
 		err = "The date format should be : dd/mm/yyyy"
 		return err
 	}
 	if (strMonth.length<1 || month<1 || month>12){
 		err = "Please enter a valid month";
 		return err;
 	}
 	if (strDay.length<1 || day<1 || day>31 || (month==2 && day>daysInFebruary(year)) || day > daysInMonth[month]){
 		err = "Please enter a valid day";
 		return err
 	}
 	if (strYear.length != 4 || year==0 || year<minYear || year>maxYear){
 		err = "Please enter a valid 4 digit year between "+minYear+" and "+maxYear;
 		return err
 	}
 	if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))==false){
 		err = "Please enter a valid date";
 		return err
 	}
    return ""
 }