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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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submitted 10 months ago* (last edited 10 months ago) by [email protected] to c/[email protected]

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[–] [email protected] 68 points 10 months ago (2 children)

Fortran, really.

In Fortran, variables beginning with the letters i through n have integer type by default, whereas all other letters imply a real-number (floating-point) variable. You can change this by declaring a type, but using i for a real is non-obvious.

(Hence the old joke, "God is real — unless declared integer.")

[–] [email protected] 28 points 10 months ago* (last edited 10 months ago) (1 children)

idk, this arbitrary i-n range behaving differently than other variables sounds like a terrible source of weird bugs to me. I don't think variable names should ever change a program's behavior.

edit:

Many old Fortran 77 programs uses these implicit rules, but you should not! The probability of errors in your program grows dramatically if you do not consistently declare your variables.

source

[–] [email protected] 22 points 10 months ago (1 children)

This comes from early years, when FORTRAN was introduced and the programmers needed to save space in the punch cards. Today, to avoid this possible source of bugs, you usually state "implicit none" in the preamble.

[–] [email protected] 17 points 10 months ago

So I’ve been an engineer doing code ports to newer versions of Fortran. I never knew why that was at the top of every file. Thank you.

[–] [email protected] 10 points 10 months ago (1 children)

Interesting. I assumed i for iterator.

[–] [email protected] 21 points 10 months ago (1 children)

i, j, k are commonly used as subscripts in linear algebra, too.

[–] [email protected] 5 points 10 months ago

i^2 = j^2 = k^2 = ijk =-1