Editing Arithmetic shift (section)

==== Handling the issue in programming languages ====

The (1999) ISO standard for the programming language [[C (programming language)|C]] defines the right shift operator in terms of divisions by powers of 2.{{sfn|ISOIEC9899|1999|loc=§ 6.5.7 Bitwise shift operators}} Because of the above-stated non-equivalence, the standard explicitly excludes from that definition the right shifts of signed numbers that have negative values.  It does not specify the behaviour of the right shift operator in such circumstances, but instead requires each individual C compiler to define the behaviour of shifting negative values right.{{#tag:ref|The C standard was intended to not restrict the C language to either ones' complement or two's complement architectures.  In cases where the behaviours of ones' complement and two's complement representations differ, such as this, the standard requires individual C compilers to document the behaviour of their target architectures.  The documentation for [[GNU Compiler Collection]] (GCC), for example, documents its behaviour as employing sign-extension.{{sfn|FSF|2008|loc=§ 4.5 Integers implementation}}|group="note"}}

Like C, C++ had an implementation-defined right shift for signed integers until C++20. Starting in the C++20 standard, right shift of a signed integer is defined to be an arithmetic shift.{{sfn|ISOCPP20|2020|loc=§ 7.6.7 Shift operators}}