expansion of $@ in a script

[jamesbon]

I have come across a small script as follows

declare -a args=( "$@" ) echo ${#args[@]}  #

this is being run as
bash demo1.sh *.pdf

where it is being checked how many pdfs are there in the directory.

I read the man page of bash which says

An indexed array is created automatically if any variable is assigned to using the syntax name[subscript]=value. The subscript is treated
as an arithmetic expression that must evaluate to a number. If subscript evaluates to a number less than zero, it is used as an offset
from one greater than the array's maximum index (so a subcript of -1 refers to the last element of the array). To explicitly declare an
indexed array, use declare -a name (see SHELL BUILTIN COMMANDS below). declare -a name[subscript] is also accepted; the subscript is
ignored.

I am not clear with 2 things

declare -a args=( "$@" )

what does this means? and what it gets evaluated to what does ("$@") mean and in the second line what does

 echo ${#args[@]}  #

gets expanded to?what is meant by ${}and args[@] expands to what

[steeldriver]

The @ mean different things depending on the context

args=( "$@" ) constructs an array called args from the script's argument list $@

See http://tldp.org/LDP/abs/html/interna...es.html#APPREF

${#args[@]} is shorthand for the number of elements in the array called args

See http://tldp.org/LDP/abs/html/arrays.html

[Vaphell]

in case one only wants to get the number of parameters, array is somewhat roundabout way to achieve that. The number of parameters script/function gets is directly accessible with $#

$ args() { echo $#; arg=( "$@" ); echo ${#arg[@]}; }
$ args *.sh
69
69