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The detailed semantics of "the" ternary operator as well as its syntax differs significantly from language to language. A top level distinction from one language to another is whether the expressions permit side effects (as in most procedural languages) and whether the language provides short-circuit evaluation semantics, whereby only the selected expression is evaluated (most standard ...
The test command in Unix evaluates the expression parameter. In most recent shell implementations, it is a shell builtin, even though the external version still exists.In the second form of the command, the [ ] (brackets) must be surrounded by blank spaces (this is because [is a program and POSIX compatible shells require a space between the program name and its arguments).
In Unix-like operating systems, true and false are commands whose only function is to always return with a predetermined exit status.Programmers and scripts often use the exit status of a command to assess success (exit status zero) or failure (non-zero) of the command.
Arithmetic if is an unstructured control statement, and is not used in structured programming. In practice it has been observed that most arithmetic IF statements reference the following statement with one or two of the labels. This was the only conditional control statement in the original implementation of Fortran on the IBM 704 computer. On ...
A language that supports the statement construct typically has rules for one or more of the following aspects: Statement terminator – marks the end of a statement; Statement separator – demarcates the boundary between two statements; need needed for the last statement; Line continuation – escapes a newline to continue a statement on the ...
In certain computer programming languages, the Elvis operator, often written ?:, is a binary operator that returns the evaluated first operand if that operand evaluates to a value likened to logically true (according to a language-dependent convention, in other words, a truthy value), and otherwise returns the evaluated second operand (in which case the first operand evaluated to a value ...
Short-circuit evaluation, minimal evaluation, or McCarthy evaluation (after John McCarthy) is the semantics of some Boolean operators in some programming languages in which the second argument is executed or evaluated only if the first argument does not suffice to determine the value of the expression: when the first argument of the AND function evaluates to false, the overall value must be ...
and | are bitwise operators that occur in many programming languages. The major difference is that bitwise operations operate on the individual bits of a binary numeral, whereas conditional operators operate on logical operations. Additionally, expressions before and after a bitwise operator are always evaluated.