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The C standard library facilities setjmp() and longjmp() can be used to simulate throwing and catching exceptions. However, these facilities bypass automatic resource management and can result in undefined behavior, commonly including resource leaks, and denial-of-service attacks.

The C++ Standard, [support.runtime], paragraph 4 , states [ ISO/IEC 14882-2014], states:

The function signature longjmp(jmp_buf jbuf, int val) has more restricted behavior in this International Standard. A setjmp/longjmp call pair has undefined behavior if replacing the setjmp and longjmp by catch and throw would invoke any non-trivial destructors for any automatic objects.

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Calling longjmp() such that it would invoke a nontrivial destructor were the call replaced with a throw expression results in undefined behavior, as demonstrated in this noncompliant code example:

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