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awk BEGIN END and string matching problem

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# 1  
Old 08-18-2009
awk BEGIN END and string matching problem
Hi,
Contents of BBS-list file:
Code:
foo
foo
foo

Code:
awk '
BEGIN { print "Analysis of \"foo\"" }
/foo/ { ++n }
END   { print "\"foo\" appears", n, "times." }' BBS-list

Output:
Code:
Analysis of "foo"
"foo" appears 3 times.

Code:
awk '
BEGIN { print "Analysis of \"foo\"" }
/foo/ { ++n }
++n
END   { print "\"foo\" appears", n, "times." }' BBS-list

Output:
Code:
Analysis of "foo"
foo 
foo
foo
"foo" appears 6 times.

Why does it print the contents of BBS-list file if i add ++n?
# 2  
Old 08-18-2009
Quote:
Originally Posted by cola
Hi,
Contents of BBS-list file:
Code:
foo
foo
foo

Code:
awk '
BEGIN { print "Analysis of \"foo\"" }
/foo/ { ++n }
END   { print "\"foo\" appears", n, "times." }' BBS-list

Output:
Code:
Analysis of "foo"
"foo" appears 3 times.

Code:
awk '
BEGIN { print "Analysis of \"foo\"" }
/foo/ { ++n }
++n
END   { print "\"foo\" appears", n, "times." }' BBS-list

Output:
Code:
Analysis of "foo"
foo 
foo
foo
"foo" appears 6 times.

Why does it print the contents of BBS-list file if i add ++n?
'++n' standing 'alone' is a condition with a missing 'action' - no corresponding '{...}'.
As '++n' (condition) is incremented and is NOT '0'. The default 'action' for a non-zero 'condition' is to print an entire current record/line.
# 3  
Old 08-18-2009
Try this as example and see the output...
1 means true, in ur example, n++ is always positive so it prints for u all records...
Code:
awk '
BEGIN { print "Analysis of \"foo\"" }
/foo/ { ++n }1' BBS-list

# 4  
Old 08-18-2009
Quote:
Originally Posted by vgersh99
'++n' standing 'alone' is a condition with a missing 'action' - no corresponding '{...}'.
As '++n' (condition) is incremented and is NOT '0'. The default 'action' for a non-zero 'condition' is to print an entire current record/line.
Thank you very much.
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