AWK ternary operator conditional statement not working

Question

I have code that checks the contents of a variable that is created from parsing a csv file. however the code below isn't working.

 $3 ~ ($2 == "\"[ABCDEFGUHIJKLMNOPQRSTUVWXYZ]\"" ? "^\"[[:digit:]]\"$" : "\"\"$") {
  print "15th field invalid-OFFENCE FILE"
}

sample data below

"ABC","A","","a" --- # This should fail because of no data in field 3
"ABC","","","a" --- # This should pass because of no data in field 2 thus it should use the else statement of empty
"ABC","A","2","a" --- # This should pass because of data in field 2 and 3

however whats actually happening is the second sample that should pass is failing and I cant for the life of me work out why

You used `$2==`, yet the content after `==` seems a regex. If you want to use regex, change to `~` instead. — Til, Mar 13 '19 at 09:47
yes it works with either but the outcome for the problem I having is the same — jordanb111, Mar 13 '19 at 09:50

Til · Accepted Answer · 2019-03-13T10:55:07.523

2

Change to this, see if it's working:

$3 ~ ($2 ~ /"[A-Z]"/ ? "^\"[[:digit:]]\"$" : "\"\"$") {
  print "15th field invalid-OFFENCE FILE"
}

To be more exact, you can further change to $2 ~ /^"[A-Z]"$/.

But with that print line you can't really see the differences.
You can change it to:

print "Line: " FNR "\t15th field invalid-OFFENCE FILE"

Then you will see the difference.

Update:
We misunderstood your meaing,
if fail means print, and pass to ignore, then this is what you wanted:

$3 ~ ($2 ~ /"[A-Z]"/ ? "\"\"$" : "^\"[[:digit:]]\"$") {
  print "Line: " FNR "\t15th field invalid-OFFENCE FILE"
}

Change the position of two branches will do.

edited Mar 13 '19 at 10:55

answered Mar 13 '19 at 09:55

Til

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no this doesn't work either its still showing the print line if the $2 and $3 is empty whereas it should be showing nothing – jordanb111 Mar 13 '19 at 10:38
so pass would mean that the program doesn't print the 15th field invalid line – jordanb111 Mar 13 '19 at 10:47

kvantour · Answer 2 · 2019-03-13T10:20:26.760

2

Looking at your script, it seems to be a bit awkward. Let's translate what you have done.

Note: I assume that you called awk with awk -F, -f file.awk inputfile

$3 ~ expr: This line attempts to match field 3 to the extended regular expression represented by expr.
($2 == "\"[ABCDEFGUHIJKLMNOPQRSTUVWXYZ]\"" ? "^\"[[:digit:]]\"$" : "\"\"$"): The used expression expr in the above ERE is a ternary operation:
- $2 == "\"[ABCDEFGUHIJKLMNOPQRSTUVWXYZ]\"": if field 2 equals the string "[ABCDEFGUHIJKLMNOPQRSTUVWXYZ]" then
- ^\"[[:digit:]]\"$": match field 3 to the ERE ^"[[:digit:]]"$, otherwise
- "\"\"$": otherwise match the empty string "".

The problem lays in the conditional of the ternary operator, which should be $2 ~ /"[A-Z]"/ instead of the equality operator.

$3 ~ ($2 ~ /"[A-Z]"/ ? "^\"[[:digit:]]\"$" : "\"\"$") {
  print "15th field invalid-OFFENCE FILE"
}

This might be more readable however:

($2 ~ /"[A-Z]"/ && $3 ~ /^"[[:digit:]]"$/) || 
  ($2 !~ /"[A-Z]"/ && $3 ~ /^""$/) { 
     print "15th field invalid-OFFENCE FILE"
}

$ awk -F, '($2 ~ /"[A-Z]"/ ? "^\"[[:digit:]]\"$" : "\"\"$")' file
"ABC","","","a"
"ABC","A","2","a"

edited Mar 13 '19 at 10:20

answered Mar 13 '19 at 09:58

kvantour

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I was using the [[ABCDEFGUHIJKLMNOPQRSTUVWXYZ] to prevent accidental match of a non locale character because of the multitude of matches that can occur in UTF 8 charset. I will check to see if your answer works though :) – jordanb111 Mar 13 '19 at 10:11
after checking neither option seems to have worked it still following the wrong regex – jordanb111 Mar 13 '19 at 10:15
2

@jordanb111 how are you invoking your `awk` command. Do you specify `FS=","`? – kvantour Mar 13 '19 at 10:16
@jordanb111 I have added my output of the command to the post. I believe it is correct. – kvantour Mar 13 '19 at 10:21
so im parsing the the csv file with ` awk -F, ' BEGIN { FPAT = "([^,]+)|(\"[^\"]+\")" } NF!=17 { print "incorrect amount of fields-OFFFENCE FILE";}` – jordanb111 Mar 13 '19 at 10:30
@jordanb111 `awk` won't match other characters other than `A` to `Z`, check [this post](https://stackoverflow.com/a/44228789/5403468) for details. Oh you are already using `-F,`, that's the right way. However when you're using `FPAT`, then be careful to check each field has `"` or not. – Til Mar 13 '19 at 10:31
the comma separating work with my code as I have the program already successfully validating 17 other fields it just this if statement that's not working i also have other ternary statements working using the method shown in my post and they work as intended – jordanb111 Mar 13 '19 at 10:33

AWK ternary operator conditional statement not working

2 Answers2