How to find the length of an array in shell?
ArraysBashShellArrays Problem Overview
How do I find the length of an array in shell?
For example:
arr=(1 2 3 4 5)
And I want to get its length, which is 5 in this case.
Arrays Solutions
Solution 1 - Arrays
$ a=(1 2 3 4)
$ echo ${#a[@]}
4
Solution 2 - Arrays
From Bash manual:
> ${#parameter} > > The length in characters of the expanded value of parameter is substituted. If parameter is ‘’ or ‘@’, the value substituted is the > number of positional parameters. If parameter is an array name > subscripted by ‘’ or ‘@’, the value substituted is the number of > elements in the array. If parameter is an indexed array name > subscripted by a negative number, that number is interpreted as > relative to one greater than the maximum index of parameter, so > negative indices count back from the end of the array, and an index of > -1 references the last element.
Length of strings, arrays, and associative arrays
string="0123456789" # create a string of 10 characters
array=(0 1 2 3 4 5 6 7 8 9) # create an indexed array of 10 elements
declare -A hash
hash=([one]=1 [two]=2 [three]=3) # create an associative array of 3 elements
echo "string length is: ${#string}" # length of string
echo "array length is: ${#array[@]}" # length of array using @ as the index
echo "array length is: ${#array[*]}" # length of array using * as the index
echo "hash length is: ${#hash[@]}" # length of array using @ as the index
echo "hash length is: ${#hash[*]}" # length of array using * as the index
output:
string length is: 10
array length is: 10
array length is: 10
hash length is: 3
hash length is: 3
Dealing with $@, the argument array:
set arg1 arg2 "arg 3"
args_copy=("$@")
echo "number of args is: $#"
echo "number of args is: ${#@}"
echo "args_copy length is: ${#args_copy[@]}"
output:
number of args is: 3
number of args is: 3
args_copy length is: 3
Solution 3 - Arrays
Assuming bash:
~> declare -a foo
~> foo[0]="foo"
~> foo[1]="bar"
~> foo[2]="baz"
~> echo ${#foo[*]}
3
So, ${#ARRAY[*]} expands to the length of the array ARRAY.
Solution 4 - Arrays
in tcsh or csh:
~> set a = ( 1 2 3 4 5 )
~> echo $#a
5
Solution 5 - Arrays
In the Fish Shell the length of an array can be found with:
$ set a 1 2 3 4
$ count $a
4
Solution 6 - Arrays
this works well for me
arglen=$#
argparam=$*
if [ $arglen -eq '3' ];
then
echo Valid Number of arguments
echo "Arguments are $*"
else
echo only four arguments are allowed
fi
Solution 7 - Arrays
For those who still searching a way to put the length of an array into a variable:
foo=$(echo ${'ARRAY[*]}