The **arithmetic IF** statement is a three-way arithmetic conditional statement, first seen in the first release of Fortran in 1957, and found in all later versions^{ [lower-alpha 1] }, and some other programming languages, such as FOCAL. Unlike the logical IF statements seen in other languages, the Fortran statement defines three different branches depending on whether the result of an expression is negative, zero, or positive, in said order, written as:

`IF(expression)negative,zero,positive`

While it originally was the only kind of IF statement provided in Fortran, the feature has been used less and less frequently after the logical IF statements were introduced, and was finally labeled obsolescent in Fortran 90. As of Fortran 2018, it is no longer required for compilers to implement arithmetic IF and it is considered to be a deleted feature. The GNU Fortran compiler has been producing warnings for arithmetic IF by default since its 9.1 release in 2019.^{[ citation needed ]}

- ↑ Might not be present in a Fortran 2018 compiler. See the Depreciation section.

**C** is a general-purpose, procedural computer programming language supporting structured programming, lexical variable scope, and recursion, with a static type system. By design, C provides constructs that map efficiently to typical machine instructions. It has found lasting use in applications previously coded in assembly language. Such applications include operating systems and various application software for computer architectures that range from supercomputers to PLCs and embedded systems.

**Fortran** is a general-purpose, compiled imperative programming language that is especially suited to numeric computation and scientific computing.

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In computer science, a **three-way comparison** takes two values A and B belonging to a type with a total order and determines whether A < B, A = B, or A > B in a single operation, in accordance with the mathematical law of trichotomy.

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