Stack: Difference between revisions

=={{header|UNIX Shell}}==

{{works with|Bourne Again SHell}}

{{works with|Zsh}}

{{works with|Korn Shell}}

<lang sh>init() { stack=(); }

push() {

local item=$1

stack=("$item" "${stack[@]}")

}

stack_top() {

# this approach sidesteps zsh indexing difference

set -- "${stack[@]}"

printf '%s\n' "$1"

}

pop() {

stack_top

stack=("${stack[@]:1}")

}

empty() {

(( ${#stack[@]} == 0 ))

}

# Demo

push fred; push wilma; push betty; push barney

printf 'peek(stack)==%s\n' "$(stack_top)"

while ! empty; do

pop

done</lang>

{{Out}}

<pre>peek(stack)==barney

barney

betty

wilma

fred</pre>