Add File Input Output in ALGOL 60

[rzuckerm]

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I Am Adding a New Code Snippet in an Existing Language

• I fixed Add File Input Output in ALGOL 60 #6004
• I did not include any extra folders/libraries
• I named the pull request using Add {PROJECT} in {LANGUAGE} format

Other Notes

This is a bit of a cheat since ALGOL 60 doesn't support file I/O. Instead it allows I/O via channel numbers. The GNU MARST ALGOL 60 to C translator has a special way to handle this using a FILE_<n> environment variable, which contains the filename for channel n. ALGOL 60 will crash with a fatal error if reading past End-Of-File (EOF). Therefore, an End-Of-Transmission (EOT) character (4) is used to signify EOF. According to my Google searches, using a sentinel value is a common way to handle this in ALGOL 60. Here's my approach:

• Write to channel 3 one line at a time
• Write EOT to channel 3
• Read channel 3 one line at a time, and output each line to stdout. A line is read one character at a time into a buffer until newline, EOT, or buffer full

Where this differs from #5744 is that the reader has no prior knowledge of how many characters to read.