Question

Application["temp"] = 8; should set the value 8 to the key temp.

However, so does Application.Contents["temp"] = 8;

So what are the differences between these two?

Thank you very much.

Answer 1

The Contents property is the default for Application, so when you use:

Application["temp"] = 8;

under the hood, the above code will be changed to call Application.Contents["temp"] = 8.

EDIT: I’ve just used Reflector and as Greg pointed out, the Contents property just returns a reference the current HttpApplicationState object. Not sure if my answer is strictly correct in this case – can someone verify this?

EDIT: OK, I found out that when you call Application["temp"] = 8; or Application.Contents["temp"] = 8; it actually call HttpApplicationState.Item. Check out this IL:

.method family hidebysig instance void Page_Load(object sender, class [mscorlib]System.EventArgs e) cil managed
{
    .maxstack 8
    L_0000: nop 
    L_0001: ldarg.0 
    L_0002: call instance class [System.Web]System.Web.HttpApplicationState [System.Web]System.Web.UI.Page::get_Application()
    L_0007: ldstr "Key"
    L_000c: ldc.i4.8 
    L_000d: box int32
    L_0012: callvirt instance void [System.Web]System.Web.HttpApplicationState::set_Item(string, object)
    L_0017: nop 
    L_0018: ldarg.0 
    L_0019: call instance class [System.Web]System.Web.HttpApplicationState [System.Web]System.Web.UI.Page::get_Application()
    L_001e: callvirt instance class [System.Web]System.Web.HttpApplicationState [System.Web]System.Web.HttpApplicationState::get_Contents()
    L_0023: ldstr "Key"
    L_0028: ldc.i4.8 
    L_0029: box int32
    L_002e: callvirt instance void [System.Web]System.Web.HttpApplicationState::set_Item(string, object)
    L_0033: nop 
    L_0034: ret 
}