我有一个如下定义的类
struct X {
X() : data() {}
int data;
enum class Zzz : int { zero, one, two };
Zzz zzz;
};
...
X xval;
xval.zzz的值是什么 - 未定义或X :: Zzz.zero？我知道对于常规枚举它将是未定义的，我想知道键入的枚举是否表现不同。
答案 0 :(得分：2)
它没有被初始化。
由于支持类型是// Create a "close" button and append it to each list item
var myNodelist = document.getElementsByTagName("LI");
var i;
for (i = 0; i < myNodelist.length; i++) {
var span = document.createElement("SPAN");
var txt = document.createTextNode("\u00D7");
span.className = "close";
span.appendChild(txt);
myNodelist[i].appendChild(span);
}
// Click on a close button to hide the current list item
var close = document.getElementsByClassName("close");
var i;
for (i = 0; i < close.length; i++) {
close[i].onclick = function() {
var div = this.parentElement;
div.style.display = "none";
}
}
function falseElement(newfe)
{
var li = document.createElement("li");
var inputValue = newfe; //document.getElementById("myInput").value;
var t = document.createTextNode(inputValue);
li.appendChild(t);
document.getElementById("myUL").appendChild(li);
var span = document.createElement("SPAN");
var txt = document.createTextNode("\u00D7");
span.className = "close";
span.appendChild(txt);
li.appendChild(span);
for (i = 0; i < close.length; i++) {
close[i].onclick = function() {
//anonymous function is the name of this type of function https://www.w3schools.com/js/js_function_definition.asp
secondelement(newfe);
var div = this.parentElement;
div.style.display = "none";
}
}
}
function secondelement(newe)
{
var li = document.createElement("li");
var inputValue = newe; //document.getElementById("myInput").value;
var t = document.createTextNode(inputValue);
li.appendChild(t);
document.getElementById("expended").appendChild(li);
var span = document.createElement("SPAN");
var txt = document.createTextNode("\u00D7");
span.className = "close";
span.appendChild(txt);
li.appendChild(span);
for (i = 0; i < close.length; i++) {
close[i].onclick = function() {
falseElement(newe);
var div = this.parentElement;
div.style.display = "none";
}
}
}
falseElement("first");
falseElement("second");
secondelement("third");
secondelement("forth");并且可以包含陷阱表示，因此在初始化之前读取<!DOCTYPE html>
<html>
<head></head>
<body>
<ul id="myUL">
</ul>
<p id="divider"><br><br></p>
<ul id="expended">
</ul>
</body>
</html> undefined 。 （出于兴趣，如果支持类型是int，xval.zzz或char，那么行为将只是实现定义。）