36 lines
1.0 KiB
Markdown
36 lines
1.0 KiB
Markdown
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Fortran stands for **For**mula **Tran**slating System - a programming language developed in 1857 at IBM.
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program hello_world.f90
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```
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program first
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implicit none
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! write 'Hello World!' to stdout
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write(*,*)"Hello world!"
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end program first
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```
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compile and run with:
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```
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$ gfortran hello_world.f90 -o hello_world
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$ ./hello_world
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```
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All code taked place between the program first and end program first statements, where first is the nmae given to the program. The `!` indicates a comment and the `write(*,*)` instructs the computer to write the statement Hello World to the screen, indicated by the first asterisk using free-format, the second asterisk. The implicit none if a very important statement as well.
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```
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program temperature
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implicit none
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! declare variables
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real :: DegC, DegF
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write(*,*)"Please type in temp in Celcius"
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! the read statement read input from
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! keyboard and stores it invariable DegC
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DegF = (9./5)*DegC + 32.
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! the write statement accepts multiple
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! strings or variables, separated
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! by commons
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```
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