Unix shell 中的数组？

You can try of the following type :

#!/bin/bash
declare -a arr


i=0
j=0


for dir in $(find /home/rmajeti/programs -type d)
do
arr[i]=$dir
i=$((i+1))
done




while [ $j -lt $i ]
do
echo ${arr[$j]}
j=$((j+1))
done

#!/bin/bash


# define a array, space to separate every item
foo=(foo1 foo2)


# access
echo "${foo[1]}"


# add or changes
foo[0]=bar
foo[2]=cat
foo[1000]=also_OK

You can read the ABS "Advanced Bash-Scripting Guide"

in bash, you create array like this

arr=(one two three)

to call the elements

$ echo "${arr[0]}"
one
$ echo "${arr[2]}"
three

to ask for user input, you can use read

read -p "Enter your choice: " choice

The Bourne shell and C shell don't have arrays, IIRC.

In addition to what others have said, in Bash you can get the number of elements in an array as follows:

elements=${#arrayname[@]}

and do slice-style operations:

arrayname=(apple banana cherry)
echo ${arrayname[@]:1}                   # yields "banana cherry"
echo ${arrayname[@]: -1}                 # yields "cherry"
echo ${arrayname[${#arrayname[@]}-1]}    # yields "cherry"
echo ${arrayname[@]:0:2}                 # yields "apple banana"
echo ${arrayname[@]:1:1}                 # yields "banana"

In ksh you do it:

set -A array element1 element2 elementn


# view the first element
echo ${array[0]}


# Amount elements (You have to substitute 1)
echo ${#array[*]}


# show last element
echo ${array[ $(( ${#array[*]} - 1 )) ]}

Try this :

echo "Find the Largest Number and Smallest Number of a given number"
echo "---------------------------------------------------------------------------------"
echo "Enter the number"
read n
i=0


while [ $n -gt 0 ] #For Seperating digits and Stored into array "x"
do
x[$i]=`expr $n % 10`
n=`expr $n / 10`
i=`expr $i + 1`
done


echo "Array values ${x[@]}"  # For displaying array elements




len=${#x[*]}  # it returns the array length




for (( i=0; i<len; i++ ))    # For Sorting array elements using Bubble sort
do
for (( j=i+1; j<len;  j++ ))
do
if [ `echo "${x[$i]} > ${x[$j]}"|bc` ]
then
t=${x[$i]}
t=${x[$i]}
x[$i]=${x[$j]}
x[$j]=$t
fi
done
done




echo "Array values ${x[*]}"  # Displaying of Sorted Array




for (( i=len-1; i>=0; i-- ))  # Form largest number
do
a=`echo $a \* 10 + ${x[$i]}|bc`
done


echo "Largest Number is : $a"


l=$a  #Largest number


s=0
while [ $a -gt 0 ]  # Reversing of number, We get Smallest number
do
r=`expr $a % 10`
s=`echo "$s * 10 + $r"|bc`
a=`expr $a / 10`
done
echo "Smallest Number is : $s" #Smallest Number


echo "Difference between Largest number and Smallest number"
echo "=========================================="
Diff=`expr $l - $s`
echo "Result is : $Diff"




echo "If you try it, We can get it"

Bourne shell doesn't support arrays. However, there are two ways to handle the issue.

Use positional shell parameters $1, $2, etc.:

$ set one two three
$ echo $*
one two three
$ echo $#
3
$ echo $2
two

Use variable evaluations:

$ n=1 ; eval a$n="one"
$ n=2 ; eval a$n="two"
$ n=3 ; eval a$n="three"
$ n=2
$ eval echo \$a$n
two

To read the values from keybord and insert element into array

# enter 0 when exit the insert element
echo "Enter the numbers"
read n
while [ $n -ne 0 ]
do
x[$i]=`expr $n`
read n
let i++
done


#display the all array elements
echo "Array values ${x[@]}"
echo "Array values ${x[*]}"


# To find the array length
length=${#x[*]}
echo $length

The following code creates and prints an array of strings in shell:

#!/bin/bash
array=("A" "B" "ElementC" "ElementE")
for element in "${array[@]}"
do
echo "$element"
done


echo
echo "Number of elements: ${#array[@]}"
echo
echo "${array[@]}"

Result:

A
B
ElementC
ElementE


Number of elements: 4


A B ElementC ElementE

If you want a key value store with support for spaces use the -A parameter:

declare -A programCollection
programCollection["xwininfo"]="to aquire information about the target window."


for program in ${!programCollection[@]}
do
echo "The program ${program} is used ${programCollection[${program}]}"
done

http://linux.die.net/man/1/bash "Associative arrays are created using declare -A name. "

An array can be loaded in twoways.

set -A TEST_ARRAY alpha beta gamma

or

X=0 # Initialize counter to zero.

-- Load the array with the strings alpha, beta, and gamma

for ELEMENT in alpha gamma beta
do
TEST_ARRAY[$X]=$ELEMENT
((X = X + 1))
done

Also, I think below information may help:

The shell supports one-dimensional arrays. The maximum number of array elements is 1,024. When an array is defined, it is automatically dimensioned to 1,024 elements. A one-dimensional array contains a sequence of array elements, which are like the boxcars connected together on a train track.

In case you want to access the array:

echo ${MY_ARRAY[2] # Show the third array element
gamma




echo ${MY_ARRAY[*] # Show all array elements
-   alpha beta gamma




echo ${MY_ARRAY[@] # Show all array elements
-  alpha beta gamma




echo ${#MY_ARRAY[*]} # Show the total number of array elements
-   3




echo ${#MY_ARRAY[@]} # Show the total number of array elements
-   3


echo ${MY_ARRAY} # Show array element 0 (the first element)
-  alpha

Your question asks about "unix shell scripting", but is tagged bash. Those are two different answers.

The POSIX specification for shells does not have anything to say about arrays, as the original Bourne shell did not support them. Even today, on FreeBSD, Ubuntu Linux, and many other systems, /bin/sh does not have array support. So if you want your script to work in different Bourne-compatible shells, you shouldn't use them. Alternatively, if you are assuming a specific shell, then be sure to put its full name in the shebang line, e.g. #!/usr/bin/env bash.

If you are using bash or zsh, or a modern version of ksh, you can create an array like this:

myArray=(first "second element" 3rd)

and access elements like this

$ echo "${myArray[1]}" # for bash/ksh; for zsh, echo $myArray[2]
second element

You can get all the elements via "${myArray[@]}". You can use the slice notation ${array[@]:start:length} to restrict the portion of the array referenced, e.g. "${myArray[@]:1}" to leave off the first element.

The length of the array is ${#myArray[@]}. You can get a new array containing all the indexes from an existing array with "${!myArray[@]}".

Older versions of ksh before ksh93 also had arrays, but not the parenthesis-based notation, nor did they support slicing. You could create an array like this, though:

set -A myArray -- first "second element" 3rd

A Simple way :

arr=("sharlock"  "bomkesh"  "feluda" )  ##declare array


len=${#arr[*]}  #determine length of array


# iterate with for loop
for (( i=0; i<len; i++ ))
do
echo ${arr[$i]}
done

There are multiple ways to create an array in shell.

ARR[0]="ABC"
ARR[1]="BCD"
echo ${ARR[*]}

${ARR[*]} prints all elements in the array.

Second way is:

ARR=("A" "B" "C" "D" 5 7 "J")
echo ${#ARR[@]}
echo ${ARR[0]}

${#ARR[@]} is used to count length of the array.