shell脚本实现冒泡排序（优化）

#!/bin/sh
#bubbling arithmetic
function bubbling(){
len=${#data[*]}
((len=len-1))
pos=0
for ((i=0;i<${#data[*]};i++))
do
flag="0" #using flag to end the foreach
# echo "${i} ${len}"
for ((j=0;j<${len};j++))
do
# echo "for to ij position ${flag} ${len}"
# echo "output data values ${data[$j]} ${data[$[j+1]]}"
if [ ${data[j]} -gt ${data[j+1]} ]
then
# echo "for to ${j} position ${flag} $[len-1]"
# data[0]=${data[$[j]]}
tmp=${data[j]} #swap array data
data[$j]=${data[j+1]}
data[$[j+1]]=${tmp}
pos=$j
flag="1"
fi
# echo "sort data are:${data[*]}"
done
len=${pos}
# echo "len and pos values are ${len} ${pos}"
if [ ${flag} -eq "0" ]
then
break
fi
done
echo ${data[*]}
#return 1
}
data=(1 5 6 9 2 6) #array data
bubbling ${data} #invoking method and by value
echo "${data[*]}" #return values

注：“$”符号表示引用变量，其中${data[$[j+1]]}和${data[${j+1}]}是不一样的，${data[$[j+1]]}表示先让j+1作运算并获取下标值，而${data[${j+1}]}仅表示获取j的下标值，关于+1它会自动忽视掉，若有更优化的算法，可以一块分享，探讨