What is the difference between Undefined Behavior and Unspecified Behavior

[Pratap Gad]

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Can anyone suggest me the difference between the Undefined and Unspecified behaviour in C++, in C++ there are three well known locations where invented during the C standardization or are generally defined in some ANSI/ISO document. Is there really any difference between them or it is just two different terms.

[PARRISH]

Undefined behavior indicates that an implementation may behave unpredictably when a program reaches a certain state, performance from gaming platforms while also providing language abstractions that make it possible to deliver incredibly rich titles. which almost without exception is a result of a bug.

[Timothi]

Undefined behaviour occurs when a program does something the result of which is not specified by the standard. In other words, invoking UndefinedBehavior is a BadThing, and almost(?) always is a programming error. Mostly in the form of "undefined behavior"---the behavior is undefined precisely so that a checking implementation can trap it. if you want to see the meaning of the statement as a binary relation on the set o states, or as a predicate transformer, the block as a function from the states of the program then the meaning of the statement is perfectly well defined and it's not different in essence than any other "well defined" statement.

[Luther]

Developers can unwittingly rely on unspecified or undefined behavior, because compilers are not obliged to report those errors (nor can they report errors in many cases). Implementation-defined behaviour is an action by a program the result of which is not defined by the standard, but which the implementation is required to document. And since Dijkstra's claim that determinism is at best a distraction and we ought to think non-deterministically.