Dash Dash The dash is a punctuation mark that is similar in appearance to and , but differs from these symbols in both length and height. The most common versions of the dash are the en dash (–), equal to half the height of the font; the em dash (—), twice as long as the en dash; and the horizontal bar (―), whose length varies across typefaces. Historically, the names of en dash and em dash were loosely related to the width of a lower-case "n" and upper-case "M", respectively, in commonly used typefaces. Usage varies both within English and in
As-if rule two exceptions concern the copying of objects, and are called copy elision and the return value optimization. The effect of the as-if rule depends on the specific compiler implementation. As an example, in the Microsoft C++ compiler, it causes omission of certain optimizations such as instruction reordering around calls to library functions, since such calls may cause input/output actions or accesses to memory locations marked , and changes in the order of those change observable behavior. The as-if rule is not specific to C++; many other programming languages, including C, Rust , Go, Ocaml, etc... -implementable in compilers- have a