/* This trivial example prints the total length
/* of the arcs in coverage %cov%
/* Run from ArcEdit

&s cov roads
edit %cov% arc
sel all

&s tmpfile1 [scratchname -prefix xxtmp1 -file]
&s tmpfile2 [scratchname -prefix xxtmp2 -file]

/* Send the results of our list command to %tmpfile1%
apc listoutput %tmpfile1%  

list length

/* Restore the list command
apc listoutput screen     

&sys perl -x%aml$file% %tmpfile1% %tmpfile2%

/* Execute the file created by our Perl program,
/* which sets the global variable .totlength

&r %tmpfile2%
					   
/* Clean up a bit...
&s x [delete %tmpfile1% -file]
&s x [delete %tmpfile2% -file]

re %cov% y

/* Now print our result!

&ty The total length of the arcs in %cov% is %.totlength%

&return /* End thread of AML execution before we hit Perl code...

/*** Our embedded Perl program follows
#!perl

# Set $in to %tmpfile1% and $out to %tmpfile2%
# @ARGV is an array holding the parameters we passed
($in,$out)=@ARGV;     

open(IN,"<$in") || die "Could not open input file $in: $!\n";
open(OUT,">$out") || die "Could not open output file $out: $!\n";

$totlength=0;

<IN>;   # Skip the first line, which is the column header

# Read each data record the file
while(<IN>) {	
	# Split the record into two fields
	($recno,$length)=split;
	
	$totlength+=$length;
}

# Create a single-line AML file that sets the global
# variable .totlength to the results of our calculation

print OUT "&s .totlength $totlength\n";