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RBBS in a Box Volume 1 #2
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RBBS_vol1_no2.iso
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014r
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reverse.zip
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REVERSE.DOC
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1988-10-01
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1KB
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22 lines
REVERSE reverses a text file line-by-line. The new file contains
every line in the original file, but in reverse order. It works
by building a table in memory of the seek position of the start of
each line in the source file. This does not require the original
file to be held in memory, so large files can be reversed.
In the second pass, the table is read backwards, and each line is
picked up at its recorded seek position, read in, and written to
the target file.
The source and target files must not be the same file! No check is
made for this condition, but any other irregular parameters are
reported and usage instructions are given.
Note the use of the TRACEx macros. I include these in all my C
programs from the start. That way, I can trace the execution of
a program at any time just be compiling it with the -DDEBUG flag
on the command line. Recompiling without that flag removes the
traces from the object code, without having to remove the trace
statements from the source code. That way they're still there next
time you change the program, in case you need to trace it again.