4

In other programming languages there often has a bool or boolean type. I can create a boolean type variable and use the not operator to toggle it. I can toggle it many times and get a series of true, false, true, false ...

In awk there is no boolean type. Only empty string and the number 0 are considered false. All other values are true. In this case what should I do if I want to do operation A on line 1, 3, 5... and operation B on line 2, 4, 6... The task will very easy if we have a boolean type variable and I can simply not it.

  • 1
    not sure if bool types are there, but you can use bitwise operations.. for example: /condition/{a = xor(a,1)} – Sundeep Sep 8 '16 at 8:46
  • 1
    Does modulo division help? NR%2 {do A} !(NR%2) {do B} – steeldriver Sep 8 '16 at 8:48
6

see How does awk '!a[$0]++' work?

basically use a=!a this will negate a turning 0 to 1 and 1 to 0.

you can test with

ls | awk '{a=!a; if ( a ) printf "good %s\n",$0 ; else printf "bad\n";}'

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.