awk referring to an array element











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#!/usr/bin/env bash
awk '
BEGIN {
arr[A]=1;
arr[B]=1;
arr[C]=1;
arr[E]=1;
arr[J]=8;
arr[Q]=10;
print arr[J]
}'


the above command outputs the latest set value for arr['subscript'], in this case 10 that is value of arr[Q] just before print and not 8 that is the value of arr[J].



Also, like in the script above, I don't want to assign values to arr['A'], arr['B'], arr['C'] and arr['E'] that have same value 1 one line at a time, rather pass an array of subscripts as one of the parameters and common value as the other parameter to a function that handles the logic of assigning them value.










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    up vote
    4
    down vote

    favorite












    #!/usr/bin/env bash
    awk '
    BEGIN {
    arr[A]=1;
    arr[B]=1;
    arr[C]=1;
    arr[E]=1;
    arr[J]=8;
    arr[Q]=10;
    print arr[J]
    }'


    the above command outputs the latest set value for arr['subscript'], in this case 10 that is value of arr[Q] just before print and not 8 that is the value of arr[J].



    Also, like in the script above, I don't want to assign values to arr['A'], arr['B'], arr['C'] and arr['E'] that have same value 1 one line at a time, rather pass an array of subscripts as one of the parameters and common value as the other parameter to a function that handles the logic of assigning them value.










    share|improve this question









    New contributor




    HarshvardhanSharma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.






















      up vote
      4
      down vote

      favorite









      up vote
      4
      down vote

      favorite











      #!/usr/bin/env bash
      awk '
      BEGIN {
      arr[A]=1;
      arr[B]=1;
      arr[C]=1;
      arr[E]=1;
      arr[J]=8;
      arr[Q]=10;
      print arr[J]
      }'


      the above command outputs the latest set value for arr['subscript'], in this case 10 that is value of arr[Q] just before print and not 8 that is the value of arr[J].



      Also, like in the script above, I don't want to assign values to arr['A'], arr['B'], arr['C'] and arr['E'] that have same value 1 one line at a time, rather pass an array of subscripts as one of the parameters and common value as the other parameter to a function that handles the logic of assigning them value.










      share|improve this question









      New contributor




      HarshvardhanSharma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      #!/usr/bin/env bash
      awk '
      BEGIN {
      arr[A]=1;
      arr[B]=1;
      arr[C]=1;
      arr[E]=1;
      arr[J]=8;
      arr[Q]=10;
      print arr[J]
      }'


      the above command outputs the latest set value for arr['subscript'], in this case 10 that is value of arr[Q] just before print and not 8 that is the value of arr[J].



      Also, like in the script above, I don't want to assign values to arr['A'], arr['B'], arr['C'] and arr['E'] that have same value 1 one line at a time, rather pass an array of subscripts as one of the parameters and common value as the other parameter to a function that handles the logic of assigning them value.







      awk array






      share|improve this question









      New contributor




      HarshvardhanSharma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      share|improve this question









      New contributor




      HarshvardhanSharma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









      share|improve this question




      share|improve this question








      edited 4 hours ago





















      New contributor




      HarshvardhanSharma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









      asked 4 hours ago









      HarshvardhanSharma

      556




      556




      New contributor




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      New contributor





      HarshvardhanSharma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.






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      Check out our Code of Conduct.






















          1 Answer
          1






          active

          oldest

          votes

















          up vote
          9
          down vote



          accepted










          Array indexes are either integers or strings in awk. What you are doing here are using variables that have not yet been initialised. Their values are therefore empty.



          You get the latest value assigned to the array because each assignment is overwriting the previous value. Using print arr[""] would also give you 10 back.



          Instead, use strings, as in arr["A"]=1.



          For your last issue: There is no real facility for initialising an awk array from the command line, but you may pass an "encoded" value that you "decode" in your BEGIN block (for example) to extract the keys and values for an array.



          Example which passes a specially delimited list as a single string and parses it to extract the indexes and values to use:



          awk -v vals="A=1:B=1:C=1:E=1:J=8:Q=10" '
          BEGIN {
          n = split(vals, v, ":")
          for (i = 1; i <= n; ++i) {
          split(v[i], a, "=")
          arr[a[1]] = a[2]
          }

          print arr["J"]
          }'


          Using separate keys and values:



          awk -v keys="A:B:C:E:J:Q" -v vals="1:1:1:1:8:10" '
          BEGIN {
          nk = split(keys, k, ":")
          nv = split(vals, v, ":")

          if (nk != nv) exit 1

          for (i = 1; i <= nk; ++i)
          arr[k[i]] = v[i]

          print arr["J"]
          }'


          This is quite a limited way of passing an "array" into awk, but it works for simple values that one has complete control over. The examples would break for any data that embeds colons (and equal signs for the 1st example) in the actual data.



          Passing data like this also means backslashes in the data will have to be treated specially (n will be a newline, so to pass the two character string n, you would have to use "\n" or '\n').



          Also related:




          • Set awk array on command line?




          As an aside, you can write a "pure awk script" like this:



          #!/usr/bin/awk -f

          BEGIN {
          # some initialisations
          }

          some_expression { some code }

          END {
          # more here
          }





          share|improve this answer























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            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes








            up vote
            9
            down vote



            accepted










            Array indexes are either integers or strings in awk. What you are doing here are using variables that have not yet been initialised. Their values are therefore empty.



            You get the latest value assigned to the array because each assignment is overwriting the previous value. Using print arr[""] would also give you 10 back.



            Instead, use strings, as in arr["A"]=1.



            For your last issue: There is no real facility for initialising an awk array from the command line, but you may pass an "encoded" value that you "decode" in your BEGIN block (for example) to extract the keys and values for an array.



            Example which passes a specially delimited list as a single string and parses it to extract the indexes and values to use:



            awk -v vals="A=1:B=1:C=1:E=1:J=8:Q=10" '
            BEGIN {
            n = split(vals, v, ":")
            for (i = 1; i <= n; ++i) {
            split(v[i], a, "=")
            arr[a[1]] = a[2]
            }

            print arr["J"]
            }'


            Using separate keys and values:



            awk -v keys="A:B:C:E:J:Q" -v vals="1:1:1:1:8:10" '
            BEGIN {
            nk = split(keys, k, ":")
            nv = split(vals, v, ":")

            if (nk != nv) exit 1

            for (i = 1; i <= nk; ++i)
            arr[k[i]] = v[i]

            print arr["J"]
            }'


            This is quite a limited way of passing an "array" into awk, but it works for simple values that one has complete control over. The examples would break for any data that embeds colons (and equal signs for the 1st example) in the actual data.



            Passing data like this also means backslashes in the data will have to be treated specially (n will be a newline, so to pass the two character string n, you would have to use "\n" or '\n').



            Also related:




            • Set awk array on command line?




            As an aside, you can write a "pure awk script" like this:



            #!/usr/bin/awk -f

            BEGIN {
            # some initialisations
            }

            some_expression { some code }

            END {
            # more here
            }





            share|improve this answer



























              up vote
              9
              down vote



              accepted










              Array indexes are either integers or strings in awk. What you are doing here are using variables that have not yet been initialised. Their values are therefore empty.



              You get the latest value assigned to the array because each assignment is overwriting the previous value. Using print arr[""] would also give you 10 back.



              Instead, use strings, as in arr["A"]=1.



              For your last issue: There is no real facility for initialising an awk array from the command line, but you may pass an "encoded" value that you "decode" in your BEGIN block (for example) to extract the keys and values for an array.



              Example which passes a specially delimited list as a single string and parses it to extract the indexes and values to use:



              awk -v vals="A=1:B=1:C=1:E=1:J=8:Q=10" '
              BEGIN {
              n = split(vals, v, ":")
              for (i = 1; i <= n; ++i) {
              split(v[i], a, "=")
              arr[a[1]] = a[2]
              }

              print arr["J"]
              }'


              Using separate keys and values:



              awk -v keys="A:B:C:E:J:Q" -v vals="1:1:1:1:8:10" '
              BEGIN {
              nk = split(keys, k, ":")
              nv = split(vals, v, ":")

              if (nk != nv) exit 1

              for (i = 1; i <= nk; ++i)
              arr[k[i]] = v[i]

              print arr["J"]
              }'


              This is quite a limited way of passing an "array" into awk, but it works for simple values that one has complete control over. The examples would break for any data that embeds colons (and equal signs for the 1st example) in the actual data.



              Passing data like this also means backslashes in the data will have to be treated specially (n will be a newline, so to pass the two character string n, you would have to use "\n" or '\n').



              Also related:




              • Set awk array on command line?




              As an aside, you can write a "pure awk script" like this:



              #!/usr/bin/awk -f

              BEGIN {
              # some initialisations
              }

              some_expression { some code }

              END {
              # more here
              }





              share|improve this answer

























                up vote
                9
                down vote



                accepted







                up vote
                9
                down vote



                accepted






                Array indexes are either integers or strings in awk. What you are doing here are using variables that have not yet been initialised. Their values are therefore empty.



                You get the latest value assigned to the array because each assignment is overwriting the previous value. Using print arr[""] would also give you 10 back.



                Instead, use strings, as in arr["A"]=1.



                For your last issue: There is no real facility for initialising an awk array from the command line, but you may pass an "encoded" value that you "decode" in your BEGIN block (for example) to extract the keys and values for an array.



                Example which passes a specially delimited list as a single string and parses it to extract the indexes and values to use:



                awk -v vals="A=1:B=1:C=1:E=1:J=8:Q=10" '
                BEGIN {
                n = split(vals, v, ":")
                for (i = 1; i <= n; ++i) {
                split(v[i], a, "=")
                arr[a[1]] = a[2]
                }

                print arr["J"]
                }'


                Using separate keys and values:



                awk -v keys="A:B:C:E:J:Q" -v vals="1:1:1:1:8:10" '
                BEGIN {
                nk = split(keys, k, ":")
                nv = split(vals, v, ":")

                if (nk != nv) exit 1

                for (i = 1; i <= nk; ++i)
                arr[k[i]] = v[i]

                print arr["J"]
                }'


                This is quite a limited way of passing an "array" into awk, but it works for simple values that one has complete control over. The examples would break for any data that embeds colons (and equal signs for the 1st example) in the actual data.



                Passing data like this also means backslashes in the data will have to be treated specially (n will be a newline, so to pass the two character string n, you would have to use "\n" or '\n').



                Also related:




                • Set awk array on command line?




                As an aside, you can write a "pure awk script" like this:



                #!/usr/bin/awk -f

                BEGIN {
                # some initialisations
                }

                some_expression { some code }

                END {
                # more here
                }





                share|improve this answer














                Array indexes are either integers or strings in awk. What you are doing here are using variables that have not yet been initialised. Their values are therefore empty.



                You get the latest value assigned to the array because each assignment is overwriting the previous value. Using print arr[""] would also give you 10 back.



                Instead, use strings, as in arr["A"]=1.



                For your last issue: There is no real facility for initialising an awk array from the command line, but you may pass an "encoded" value that you "decode" in your BEGIN block (for example) to extract the keys and values for an array.



                Example which passes a specially delimited list as a single string and parses it to extract the indexes and values to use:



                awk -v vals="A=1:B=1:C=1:E=1:J=8:Q=10" '
                BEGIN {
                n = split(vals, v, ":")
                for (i = 1; i <= n; ++i) {
                split(v[i], a, "=")
                arr[a[1]] = a[2]
                }

                print arr["J"]
                }'


                Using separate keys and values:



                awk -v keys="A:B:C:E:J:Q" -v vals="1:1:1:1:8:10" '
                BEGIN {
                nk = split(keys, k, ":")
                nv = split(vals, v, ":")

                if (nk != nv) exit 1

                for (i = 1; i <= nk; ++i)
                arr[k[i]] = v[i]

                print arr["J"]
                }'


                This is quite a limited way of passing an "array" into awk, but it works for simple values that one has complete control over. The examples would break for any data that embeds colons (and equal signs for the 1st example) in the actual data.



                Passing data like this also means backslashes in the data will have to be treated specially (n will be a newline, so to pass the two character string n, you would have to use "\n" or '\n').



                Also related:




                • Set awk array on command line?




                As an aside, you can write a "pure awk script" like this:



                #!/usr/bin/awk -f

                BEGIN {
                # some initialisations
                }

                some_expression { some code }

                END {
                # more here
                }






                share|improve this answer














                share|improve this answer



                share|improve this answer








                edited 4 hours ago

























                answered 4 hours ago









                Kusalananda

                119k16224366




                119k16224366






















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