How to compile f90 files using Brew?

I downloaded Brew, and downloaded GCC from it. I didn't know what file to use, so I went with a text editor file that I renamed FortranTest.f90

Ran it in the compiler and and got this error:

1 | {\rtf1\ansi\ansicpg1252\cocoartf2759
      |  1
Error: Invalid character in name at (1)
/Users/BLANK/Desktop/FortranTest.f90:2:2:

    2 | \cocoatextscaling0\cocoaplatform0{\fonttbl\f0\fswiss\fcharset0 Helvetica;}
      |  1
Error: Invalid character in name at (1)
/Users/BLANK/Desktop/FortranTest.f90:2:74:

    2 | \cocoatextscaling0\cocoaplatform0{\fonttbl\f0\fswiss\fcharset0 Helvetica;}
      |                                                                          1
Error: Invalid character in name at (1)
/Users/BLANK/Desktop/FortranTest.f90:3:2:

    3 | {\colortbl;\red255\green255\blue255;}
      |  1
Error: Invalid character in name at (1)
/Users/BLANK/Desktop/FortranTest.f90:3:13:

    3 | {\colortbl;\red255\green255\blue255;}
      |             1
Error: Invalid character in name at (1)
/Users/BLANK/Desktop/FortranTest.f90:3:37:

    3 | {\colortbl;\red255\green255\blue255;}
      |                                     1
Error: Invalid character in name at (1)
/Users/BLANK/Desktop/FortranTest.f90:4:2:

    4 | {\*\expandedcolortbl;;}
      |  1
Error: Invalid character in name at (1)
/Users/BLANK/Desktop/FortranTest.f90:4:23:

    4 | {\*\expandedcolortbl;;}
      |                       1
Error: Invalid character in name at (1)
/Users/BLANK/Desktop/FortranTest.f90:5:2:

    5 | \margl1440\margr1440\vieww11520\viewh8400\viewkind0
      |  1
Error: Invalid character in name at (1)
/Users/BLANK/Desktop/FortranTest.f90:6:2:

    6 | \pard\tx720\tx1440\tx2160\tx2880\tx3600\tx4320\tx5040\tx5760\tx6480\tx7200\tx7920\tx8640\pardirnatural\partightenfactor0
      |  1
Error: Invalid character in name at (1)
/Users/BLANK/Desktop/FortranTest.f90:8:2:

    8 | \f0\fs24 \cf0 program f90_Test\
      |  1
Error: Invalid character in name at (1)
/Users/BLANK/Desktop/FortranTest.f90:9:1:

    9 | \
      | 1
Error: Invalid character in name at (1)
/Users/BLANK/Desktop/FortranTest.f90:11:1:

   11 | \
      | 1
Error: Invalid character in name at (1)
/Users/BLANK/Desktop/FortranTest.f90:12:14:

   12 | print *, TEXT\
      |              1
Error: Syntax error in PRINT statement at (1)
/Users/BLANK/Desktop/FortranTest.f90:13:1:

   13 | \
      | 1
Error: Invalid character in name at (1)
/Users/BLANK/Desktop/FortranTest.f90:14:21:

   14 | end program f90_Test}
      |                     1
Error: Syntax error in END PROGRAM statement at (1)

The EXACT error (I copied it) please help! Tell me if I did it wrong!

The file contents were:

program f90_Test

char TEXT = "HELLO WORLD"

print *, TEXT

end program f90_Test

Solution

You have saved your file as a .rtf document, then renamed it to .f90. This means, your compiler received gibberish instead of Fortran code. You have to save it as plain text in the first place, or use some conversion tool. Rich Text (.rtf) documents contain formatting instructions that tell your editor which fonts you want to use, where to bold, etc... and it is not something a Fortran compiler can understand.

To that end — TextEdit is a very bad choice for a code editor. Popular choices on Mac are nano, vim, emacs, Visual Studio Code, TextMate, Sublime Text, and more. Your Mac comes with nano and vim preinstalled. nano compared to vim is like a tricycle compared to a space shuttle: both get you places, but one is much more powerful — and complicated — than the other.