是否有可能在c++的for循环的初始化体中声明两个不同类型的变量?
例如:
for(int i=0,j=0 ...
定义两个整数。我可以在初始化体中定义int和char吗?如何做到这一点呢?
是否有可能在c++的for循环的初始化体中声明两个不同类型的变量?
例如:
for(int i=0,j=0 ...
定义两个整数。我可以在初始化体中定义int和char吗?如何做到这一点呢?
class my_class
{
...
my_class(my_class const &) = delete;
...
};
在这种情况下= delete是什么意思?
是否有其他“修饰符”(除了= 0和= delete)?
来自标准库的objective .swift文件在第228行左右包含以下几行代码:
extension NSObject : Equatable, Hashable {
/// ...
open var hashValue: Int {
return hash
}
}
在这个上下文中open var是什么意思，或者open关键字一般是什么?
在JavaScript中，可以像这样声明多个变量:
var variable1 = "Hello, World!";
var variable2 = "Testing...";
var variable3 = 42;
.．.或者像这样:
var variable1 = "Hello, World!",
variable2 = "Testing...",
variable3 = 42;
一种方法比另一种更好/更快吗?
为什么C中需要挥发性?它的用途是什么?它会做什么?
是否可以在JavaScript函数中定义全局变量?
我想在其他函数中使用trailimage变量(在makeObj函数中声明)。
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title></title>
<script type="text/javascript">
var offsetfrommouse = [10, -20];
var displayduration = 0;
var obj_selected = 0;
function makeObj(address) {
**var trailimage = [address, 50, 50];**
document.write('<img id="trailimageid" src="' + trailimage[0] + '" border="0" style=" position: absolute; visibility:visible; left: 0px; top: 0px; width: ' + trailimage[1] + 'px; height: ' + trailimage[2] + 'px">');
obj_selected = 1;
}
function truebody() {
return (!window.opera && document.compatMode && document.compatMode != "BackCompat") ? document.documentElement : document.body;
}
function hidetrail() {
var x = document.getElementById("trailimageid").style;
x.visibility = "hidden";
document.onmousemove = "";
}
function followmouse(e) {
var xcoord = offsetfrommouse[0];
var ycoord = offsetfrommouse[1];
var x = document.getElementById("trailimageid").style;
if (typeof e != "undefined") {
xcoord += e.pageX;
ycoord += e.pageY;
}
else if (typeof window.event != "undefined") {
xcoord += truebody().scrollLeft + event.clientX;
ycoord += truebody().scrollTop + event.clientY;
}
var docwidth = 1395;
var docheight = 676;
if (xcoord + trailimage[1] + 3 > docwidth || ycoord + trailimage[2] > docheight) {
x.display = "none";
alert("inja");
}
else
x.display = "";
x.left = xcoord + "px";
x.top = ycoord + "px";
}
if (obj_selected = 1) {
alert("obj_selected = true");
document.onmousemove = followmouse;
if (displayduration > 0)
setTimeout("hidetrail()", displayduration * 1000);
}
</script>
</head>
<body>
<form id="form1" runat="server">
<img alt="" id="house" src="Pictures/sides/right.gif" style="z-index: 1; left: 372px;
top: 219px; position: absolute; height: 138px; width: 120px" onclick="javascript:makeObj('Pictures/sides/sides-not-clicked.gif');" />
</form>
</body>
</html>
在这样的声明中const的含义是什么？这个常数使我困惑。
class foobar
{
public:
operator int () const;
const char* foo() const;
};
像这样声明一个数组的真正区别是什么:
var myArray = new Array();
and
var myArray = [];