Looping over arrays printing both index and value

Question

I want to do something like this   foo     foo 0   bar  foo 35   baz  for  i 0 i lt    foo     i     do     echo   i    foo  i    done   Output    0  bar   1     Then i tried to loop through it using for in   foo     foo 0   bar  foo 35   baz  for i in   foo     do     echo      i  done   Output       bar      naz   but here I don t know the index value   I know you could something like  foo     foo 0   bar  foo 35   baz  declare -p foo   Output    declare -a foo    0   bar   35   baz      but  can t you do it in another way

User · Answer

you can always use iteration param   ITER 0 for I in   FOO     do       echo   I    ITER      ITER   expr  ITER   1  done

User · Answer

In bash 4  you can use associative arrays   declare -A foo foo 0   bar  foo 35   baz  for key in     foo      do     echo  key   key  value    foo  key    done    output     key  0  value bar      key  35  value baz    In bash 3  this works  also works in zsh    map     map    0 bar   map    35 baz    for keyvalue in    map        do     key   keyvalue          value   keyvalue         echo  key   key  value  value   done

User · Answer

Simple one line trick for dumping array  I ve added one value with spaces   foo    foo 12   bar  foo 42   foo bar baz  foo 35   baz    I  for quickly dump bash arrays or associative arrays I use  This one line command   paste  lt  printf   s n      foo        lt  printf   s n     foo           Will render   12  bar 35  baz 42  foo bar baz   Explained   printf   s n      foo      will print all keys separated by a newline  printf   s n     foo      will print all values separated by a newline  paste  lt  cmd1   lt  cmd2  will merge output of cmd1 and cmd2 line by line    Tunning  This could be tunned by -d switch   paste -d    lt  printf   s n      foo        lt  printf   s n     foo       12 bar 35 baz 42 foo bar baz   or even   paste -d    lt  printf  foo  s  n      foo        lt  printf    s  n     foo       foo 12   bar  foo 35   baz  foo 42   foo bar baz    Associative array will work same   declare -A bar   foo  snoopy  bar  nice  baz  cool  foo bar   Hello world    paste -d    lt  printf  bar  s  n      bar        lt  printf    s  n     bar       bar foo bar   Hello world   bar foo   snoopy  bar bar   nice  bar baz   cool    Issue with newlines or special chars  Unfortunely  there is at least one condition making this not work anymore  when variable do contain newline   foo 17    There is one nnewline    Command paste will merge line-by-line  so output will become wrong   paste -d    lt  printf  foo  s  n      foo        lt  printf    s  n     foo       foo 12   bar  foo 17   There is one foo 35  newline  foo 42   baz    foo bar baz    For this work  you could use  q instead of  s in second printf command  and whipe quoting    paste -d    lt  printf  foo  s  n      foo        lt  printf   q n     foo         Will render perfect   foo 12  bar foo 17    There is one nnewline  foo 35  baz foo 42  foo  bar  baz   From man bash               q     causes  printf  to output the corresponding argument in a                  format that can be reused as shell input

User · Answer

You would find the array keys with     foo       reference   so   for i in     foo       do    printf   s t s n    i     foo  i    done   Which means that indices will be in  i while the elements themselves have to be accessed via   foo  i

User · Answer

INDEX 0 for i in  list  do      echo   INDEX   i     let INDEX   INDEX  1 done

User · Answer

users   kamal   jamal   rahim   karim   sadia   index    t -1  for i in   users      do   t     t   1      if    t -eq 0    then     for j in    users      do       index  j   j     done   fi   echo    index  t   is  i  done

[bash] Looping over arrays, printing both index and value

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