// this function is from http://www.robertnyman.com/2005/11/07/the-ultimate-getelementsbyclassname/
function getElementsByClassName(oElm, strTagName, strClassName){
    var arrElements = (strTagName == "*" && oElm.all)? oElm.all : oElm.getElementsByTagName(strTagName);
    var arrReturnElements = new Array();
    strClassName = strClassName.replace(/\-/g, "\\-");
    var oRegExp = new RegExp("(^|\\s)" + strClassName + "(\\s|$)");
    var oElement;
    for(var i=0; i<arrElements.length; i++){
        oElement = arrElements[i];      
        if(oRegExp.test(oElement.className)){
            arrReturnElements.push(oElement);
        }   
    }
    return (arrReturnElements)
}

var f = true;
var orig_val = new Array();

function f2c(degreesf){
        celsius = 5/9 * (Number(degreesf) - 32);
        return String(celsius);
}

function switchcf(){
        var objs = getElementsByClassName(document, "span", "temper");
        if (f == true){
                f = false;
                var i = 0;
                for (i = 0; i < objs.length; i++){
                        var str = objs[i].lastChild.nodeValue;
                        orig_val[i] = str;
                        var celsius = f2c(str.substring(0, str.indexOf("F") - 1));
                        objs[i].lastChild.nodeValue = celsius.substring(0, 5) + " C" + str.substring(str.indexOf("F") + 1, 99);
                }
        }
        else{
                f = true;
                var i = 0;
                for (i = 0; i < objs.length; i++){
                        objs[i].lastChild.nodeValue = orig_val[i];
                }
        }

}