Why do we have only costant value's or constant value expression in SWITCH statement

[_uj]

What?

What does "case labels are evaluated without order" mean?

The only difference between switch and FORTRAN's computed GOTO is syntactic sugar. I could do anything that switch can do in FORTRAN. The only complication is that I would need to map (the used values of) the switch variable on to a consecutive sequence of integer values starting at one. That the compiler in C++ does this for me is, as I said, syntactic sugar.

You can implement any control structure available in C++ in assembly and that would involve gotos. So if you would call all control structures "glorified gotos" I would agree, but if you single out the switch, I don't.

As a control structure the switch has a unique property. The label cases are in no specific order. That's what characterizes a switch and that's for example why an if-chain isn't functionally equivalent with a switch. That's also why a switch can be implemented in O(1) using say a table of some kind.

The fact that you (or a compiler) can accomplish the functional equivalent of a switch with gotos in some language is irrelevant. The switch has a unique property that no combination of other control structures can mimic. It's not just a "glorified goto".