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Top Forums Shell Programming and Scripting Strange behaviour of arrays in awk Post 302852379 by ripat on Wednesday 11th of September 2013 12:46:09 PM
Old 09-11-2013
Quote:
Originally Posted by Scrutinizer
This is not only a condition, but it also creates an array element code[$3] with an empty value
Indeed and that's exactly what I find weird. With code[$3] in the second block I was expecting awk to *evaluate* the value of code[$3] *not* to assign any value to it, albeit NULL.

Code:
awk 'foo="bar"{print "block 1"} END{print foo}' f1

Returns bar.

foo="bar" assigns "bar" to foo and returns a TRUE. No problem with that. But in the condition of the second block code[$3] there is no assignment sign and it still assigns a value. I can't stop finding it weird.

Furthermore, if you look to my code above and its return.

Code:
FNR == NR && /file1_l1/ {
	code[$2] = 1
	next
}

code[$3] {
	print
}

Code:
code[file1_l3_c3]=
code[code_to_find]=1
code[file2_code3]=
code[file1_l2_c3]=
code[file2_code5]=

The instruction next should make the program to loop on the first file until it reaches the end of file1. Then it continues with the second file, right? I understand that the condition of the second block assigns a value while evaluating code[$3] but how come that it assigns values from the first file as the pointer NR is already on the second file? See my point?

Last edited by ripat; 09-11-2013 at 02:36 PM.. Reason: More confusion...
 

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PRINT(3)								 1								  PRINT(3)

print - Output a string

SYNOPSIS
int print (string $arg) DESCRIPTION
Outputs $arg. print is not actually a real function (it is a language construct) so you are not required to use parentheses with its argument list. PARAMETERS
o $arg - The input data. RETURN VALUES
Returns 1, always. EXAMPLES
Example #1 print examples <?php print("Hello World"); print "print() also works without parentheses."; print "This spans multiple lines. The newlines will be output as well"; print "This spans multiple lines. The newlines will be output as well."; print "escaping characters is done "Like this"."; // You can use variables inside a print statement $foo = "foobar"; $bar = "barbaz"; print "foo is $foo"; // foo is foobar // You can also use arrays $bar = array("value" => "foo"); print "this is {$bar['value']} !"; // this is foo ! // Using single quotes will print the variable name, not the value print 'foo is $foo'; // foo is $foo // If you are not using any other characters, you can just print variables print $foo; // foobar print <<<END This uses the "here document" syntax to output multiple lines with $variable interpolation. Note that the here document terminator must appear on a line with just a semicolon no extra whitespace! END; ?> NOTES
Note Because this is a language construct and not a function, it cannot be called using variable functions. SEE ALSO
echo(3), printf(3), flush(3), Heredoc syntax. PHP Documentation Group PRINT(3)
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