blocks|key|103456|text|Bash没有多维数组。但是您可以使用关联数组来模拟类似的效果。下面是一个伪装成多维数组的关联数组示例：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|103457|declare+-A+arr
arr[0,0]=0
arr[0,1]=1
arr[1,0]=2
arr[1,1]=3
echo+"${arr[0,0]}+${arr[0,1]}"+#+will+print+0+1|code-block|syntax|javascript|103458|如果不将数组声明为关联数组(使用-A)，上述方法将不起作用。例如，如果省略declare+-A+arr行，echo将打印2+3而不是0+1，因为0,0、1,0等将被视为算术表达式并计算为0+(逗号运算符右侧的值)。|offset|length|style|CODE|103459|entityMap^0|0|0|G|2|11|E|1H|4|1O|3|1U|3|20|3|24|3|2L|1|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]|$I|V|J|W|K|L]|$I|X|J|Y|K|L]|$I|Z|J|10|K|L]|$I|11|J|12|K|L]|$I|13|J|14|K|L]|$I|15|J|16|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|17|8|@]|9|@]|A|$]]]|N|$]]

Bash doesn't have multi-dimensional array. But you can simulate a somewhat similar effect with associative arrays. The following is an example of associative array pretending to be used as multi-dimensional array:

<pre><code>declare -A arr
arr[0,0]=0
arr[0,1]=1
arr[1,0]=2
arr[1,1]=3
echo "${arr[0,0]} ${arr[0,1]}" # will print 0 1
</code></pre>

If you don't declare the array as associative (with <code>-A</code>), the above won't work. For example, if you omit the <code>declare -A arr</code> line, the <code>echo</code> will print <code>2 3</code> instead of <code>0 1</code>, because <code>0,0</code>, <code>1,0</code> and such will be taken as arithmetic expression and evaluated to <code>0</code> (the value to the right of the comma operator).

blocks|key|320361|text|您也可以用一种不太聪明的方式来实现这一点。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|320362|q=()
q%2B=(+1-2+)
q%2B=(+a-b+)

for+set+in+${q[@]};
do
echo+${set%25%25-*}
echo+${set##*-}
done|code-block|syntax|javascript|320363|当然，22行的解决方案或间接的解决方案可能是更好的方法，为什么不在每个地方都使用eval。|320364|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You can also approach this in a much less smarter fashion 

<pre><code>q=()
q+=( 1-2 )
q+=( a-b )

for set in ${q[@]};
do
echo ${set%%-*}
echo ${set##*-}
done
</code></pre>

of course a 22 line solution or indirection is probably the better way to go and why not sprinkle eval every where to .

blocks|key|103573|text|另一种方法是您可以将每一行表示为字符串，即将2D数组映射到1D数组。然后，当您进行编辑时，您需要做的就是对行的字符串进行解包和重新打包：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|103574|#+Init+a+4x5+matrix
a=("00+01+02+03+04"+"10+11+12+13+14"+"20+21+22+23+24"+"30+31+32+33+34")

aset()+{
++row=$1
++col=$2
++value=$3
++IFS='+'+read+-r+-a+tmp+<<<+"${a[$row]}"
++tmp[$col]=$value
++a[$row]="${tmp[@]}"
}

#+Set+a[2][3]+=+9999
aset+2+3+9999

#+Show+result
for+r+in+"${a[@]}";+do
++echo+$r
done|code-block|syntax|javascript|103575|输出：|103576|00+01+02+03+04
10+11+12+13+14
20+21+22+9999+24
30+31+32+33+34|103577|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Another approach is you can represent each row as a string, i.e. mapping the 2D array into an 1D array. Then, all you need to do is unpack and repack the row's string whenever you make an edit:

<pre><code># Init a 4x5 matrix
a=("00 01 02 03 04" "10 11 12 13 14" "20 21 22 23 24" "30 31 32 33 34")

aset() {
 row=$1
 col=$2
 value=$3
 IFS=' ' read -r -a tmp &lt;&lt;&lt; "${a[$row]}"
 tmp[$col]=$value
 a[$row]="${tmp[@]}"
}

# Set a[2][3] = 9999
aset 2 3 9999

# Show result
for r in "${a[@]}"; do
 echo $r
done
</code></pre>

Outputs:

<pre><code>00 01 02 03 04
10 11 12 13 14
20 21 22 9999 24
30 31 32 33 34
</code></pre>

blocks|key|103516|text|一种在bash中模拟数组的方法(它可以适用于任何维数的数组)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|103517|#!/bin/bash

##+The+following+functions+implement+vectors+(arrays)+operations+in+bash:
##+Definition+of+a+vector+<v>:
##++++++v_0+-+variable+that+stores+the+number+of+elements+of+the+vector
##++++++v_1..v_n,+where+n=v_0+-+variables+that+store+the+values+of+the+vector+elements

VectorAddElementNext+()+{
#+Vector+Add+Element+Next
#+Adds+the+string+contained+in+variable+$2+in+the+next+element+position+(vector+length+%2B+1)+in+vector+$1

++++local+elem_value
++++local+vector_length
++++local+elem_name

++++eval+elem_value=\"\$$2\"
++++eval+vector_length=\$$1\_0
++++if+[+-z+"$vector_length"+];+then
++++++++vector_length=$((0))
++++fi

++++vector_length=$((+vector_length+%2B+1+))
++++elem_name=$1_$vector_length

++++eval+$elem_name=\"\$elem_value\"
++++eval+$1_0=$vector_length
}

VectorAddElementDVNext+()+{
#+Vector+Add+Element+Direct+Value+Next
#+Adds+the+string+$2+in+the+next+element+position+(vector+length+%2B+1)+in+vector+$1

++++local+elem_value
++++local+vector_length
++++local+elem_name

++++eval+elem_value="$2"
++++eval+vector_length=\$$1\_0
++++if+[+-z+"$vector_length"+];+then
++++++++vector_length=$((0))
++++fi

++++vector_length=$((+vector_length+%2B+1+))
++++elem_name=$1_$vector_length

++++eval+$elem_name=\"\$elem_value\"
++++eval+$1_0=$vector_length
}

VectorAddElement+()+{
#+Vector+Add+Element
#+Adds+the+string+contained+in+the+variable+$3+in+the+position+contained+in+$2+(variable+or+direct+value)+in+the+vector+$1

++++local+elem_value
++++local+elem_position
++++local+vector_length
++++local+elem_name

++++eval+elem_value=\"\$$3\"
++++elem_position=$(($2))
++++eval+vector_length=\$$1\_0
++++if+[+-z+"$vector_length"+];+then
++++++++vector_length=$((0))
++++fi

++++if+[+$elem_position+-ge+$vector_length+];+then
++++++++vector_length=$elem_position
++++fi

++++elem_name=$1_$elem_position

++++eval+$elem_name=\"\$elem_value\"
++++if+[+!+$elem_position+-eq+0+];+then
++++++++eval+$1_0=$vector_length
++++fi
}

VectorAddElementDV+()+{
#+Vector+Add+Element
#+Adds+the+string+$3+in+the+position+$2+(variable+or+direct+value)+in+the+vector+$1

++++local+elem_value
++++local+elem_position
++++local+vector_length
++++local+elem_name

++++eval+elem_value="$3"
++++elem_position=$(($2))
++++eval+vector_length=\$$1\_0
++++if+[+-z+"$vector_length"+];+then
++++++++vector_length=$((0))
++++fi

++++if+[+$elem_position+-ge+$vector_length+];+then
++++++++vector_length=$elem_position
++++fi

++++elem_name=$1_$elem_position

++++eval+$elem_name=\"\$elem_value\"
++++if+[+!+$elem_position+-eq+0+];+then
++++++++eval+$1_0=$vector_length
++++fi
}

VectorPrint+()+{
#+Vector+Print
#+Prints+all+the+elements+names+and+values+of+the+vector+$1+on+sepparate+lines

++++local+vector_length

++++vector_length=$(($1_0))
++++if+[+"$vector_length"+=+"0"+];+then
++++++++echo+"Vector+\"$1\"+is+empty!"
++++else
++++++++echo+"Vector+\"$1\":"
++++++++for+((i=1;+i<=$vector_length;+i%2B%2B));+do
++++++++++++eval+echo+\"[$i]:+\\\"\$$1\_$i\\\"\"
++++++++++++###OR:+eval+printf+\'\%25s\\\n\'+\"[\$i]:+\\\"\$$1\_$i\\\"\"
++++++++done
++++fi
}

VectorDestroy+()+{
#+Vector+Destroy
#+Empties+all+the+elements+values+of+the+vector+$1

++++local+vector_length

++++vector_length=$(($1_0))
++++if+[+!+"$vector_length"+=+"0"+];+then
++++++++for+((i=1;+i<=$vector_length;+i%2B%2B));+do
++++++++++++unset+$1_$i
++++++++done
++++++++unset+$1_0
++++fi
}

##################
###+MAIN+START+###
##################

##+Setting+vector+'params'+with+all+the+parameters+received+by+the+script:
for+((i=1;+i<=$#;+i%2B%2B));+do
++++eval+param="\${$i}"
++++VectorAddElementNext+params+param
done

#+Printing+the+vector+'params':
VectorPrint+params

read+temp

##+Setting+vector+'params2'+with+the+elements+of+the+vector+'params'+in+reversed+order:
if+[+-n+"$params_0"+];+then
++++for+((i=1;+i<=$params_0;+i%2B%2B));+do
++++++++count=$((params_0-i%2B1))
++++++++VectorAddElement+params2+count+params_$i
++++done
fi

#+Printing+the+vector+'params2':
VectorPrint+params2

read+temp

##+Getting+the+values+of+'params2'`s+elements+and+printing+them:
if+[+-n+"$params2_0"+];+then
++++echo+"Printing+the+elements+of+the+vector+'params2':"
++++for+((i=1;+i<=$params2_0;+i%2B%2B));+do
++++++++eval+current_elem_value=\"\$params2\_$i\"
++++++++echo+"params2_$i=\"$current_elem_value\""
++++done
else
++++echo+"Vector+'params2'+is+empty!"
fi

read+temp

##+Creating+a+two+dimensional+array+('a'):
for+((i=1;+i<=10;+i%2B%2B));+do
++++VectorAddElement+a+0+i
++++for+((j=1;+j<=8;+j%2B%2B));+do
++++++++value=$((+8+*+(+i+-+1+)+%2B+j+))
++++++++VectorAddElementDV+a_$i+$j+$value
++++done
done

##+Manually+printing+the+two+dimensional+array+('a'):
echo+"Printing+the+two-dimensional+array+'a':"
if+[+-n+"$a_0"+];+then
++++for+((i=1;+i<=$a_0;+i%2B%2B));+do
++++++++eval+current_vector_lenght=\$a\_$i\_0
++++++++if+[+-n+"$current_vector_lenght"+];+then
++++++++++++for+((j=1;+j<=$current_vector_lenght;+j%2B%2B));+do
++++++++++++++++eval+value=\"\$a\_$i\_$j\"
++++++++++++++++printf+"$value+"
++++++++++++done
++++++++fi
++++++++printf+"\n"
++++done
fi

################
###+MAIN+END+###
################|code-block|syntax|javascript|103518|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

A way to simulate arrays in bash (it can be adapted for any number of dimensions of an array):

<pre><code>#!/bin/bash

## The following functions implement vectors (arrays) operations in bash:
## Definition of a vector &lt;v&gt;:
## v_0 - variable that stores the number of elements of the vector
## v_1..v_n, where n=v_0 - variables that store the values of the vector elements

VectorAddElementNext () {
# Vector Add Element Next
# Adds the string contained in variable $2 in the next element position (vector length + 1) in vector $1

 local elem_value
 local vector_length
 local elem_name

 eval elem_value=\"\$$2\"
 eval vector_length=\$$1\_0
 if [ -z "$vector_length" ]; then
 vector_length=$((0))
 fi

 vector_length=$(( vector_length + 1 ))
 elem_name=$1_$vector_length

 eval $elem_name=\"\$elem_value\"
 eval $1_0=$vector_length
}

VectorAddElementDVNext () {
# Vector Add Element Direct Value Next
# Adds the string $2 in the next element position (vector length + 1) in vector $1

 local elem_value
 local vector_length
 local elem_name

 eval elem_value="$2"
 eval vector_length=\$$1\_0
 if [ -z "$vector_length" ]; then
 vector_length=$((0))
 fi

 vector_length=$(( vector_length + 1 ))
 elem_name=$1_$vector_length

 eval $elem_name=\"\$elem_value\"
 eval $1_0=$vector_length
}

VectorAddElement () {
# Vector Add Element
# Adds the string contained in the variable $3 in the position contained in $2 (variable or direct value) in the vector $1

 local elem_value
 local elem_position
 local vector_length
 local elem_name

 eval elem_value=\"\$$3\"
 elem_position=$(($2))
 eval vector_length=\$$1\_0
 if [ -z "$vector_length" ]; then
 vector_length=$((0))
 fi

 if [ $elem_position -ge $vector_length ]; then
 vector_length=$elem_position
 fi

 elem_name=$1_$elem_position

 eval $elem_name=\"\$elem_value\"
 if [ ! $elem_position -eq 0 ]; then
 eval $1_0=$vector_length
 fi
}

VectorAddElementDV () {
# Vector Add Element
# Adds the string $3 in the position $2 (variable or direct value) in the vector $1

 local elem_value
 local elem_position
 local vector_length
 local elem_name

 eval elem_value="$3"
 elem_position=$(($2))
 eval vector_length=\$$1\_0
 if [ -z "$vector_length" ]; then
 vector_length=$((0))
 fi

 if [ $elem_position -ge $vector_length ]; then
 vector_length=$elem_position
 fi

 elem_name=$1_$elem_position

 eval $elem_name=\"\$elem_value\"
 if [ ! $elem_position -eq 0 ]; then
 eval $1_0=$vector_length
 fi
}

VectorPrint () {
# Vector Print
# Prints all the elements names and values of the vector $1 on sepparate lines

 local vector_length

 vector_length=$(($1_0))
 if [ "$vector_length" = "0" ]; then
 echo "Vector \"$1\" is empty!"
 else
 echo "Vector \"$1\":"
 for ((i=1; i&lt;=$vector_length; i++)); do
 eval echo \"[$i]: \\\"\$$1\_$i\\\"\"
 ###OR: eval printf \'\%s\\\n\' \"[\$i]: \\\"\$$1\_$i\\\"\"
 done
 fi
}

VectorDestroy () {
# Vector Destroy
# Empties all the elements values of the vector $1

 local vector_length

 vector_length=$(($1_0))
 if [ ! "$vector_length" = "0" ]; then
 for ((i=1; i&lt;=$vector_length; i++)); do
 unset $1_$i
 done
 unset $1_0
 fi
}

##################
### MAIN START ###
##################

## Setting vector 'params' with all the parameters received by the script:
for ((i=1; i&lt;=$#; i++)); do
 eval param="\${$i}"
 VectorAddElementNext params param
done

# Printing the vector 'params':
VectorPrint params

read temp

## Setting vector 'params2' with the elements of the vector 'params' in reversed order:
if [ -n "$params_0" ]; then
 for ((i=1; i&lt;=$params_0; i++)); do
 count=$((params_0-i+1))
 VectorAddElement params2 count params_$i
 done
fi

# Printing the vector 'params2':
VectorPrint params2

read temp

## Getting the values of 'params2'`s elements and printing them:
if [ -n "$params2_0" ]; then
 echo "Printing the elements of the vector 'params2':"
 for ((i=1; i&lt;=$params2_0; i++)); do
 eval current_elem_value=\"\$params2\_$i\"
 echo "params2_$i=\"$current_elem_value\""
 done
else
 echo "Vector 'params2' is empty!"
fi

read temp

## Creating a two dimensional array ('a'):
for ((i=1; i&lt;=10; i++)); do
 VectorAddElement a 0 i
 for ((j=1; j&lt;=8; j++)); do
 value=$(( 8 * ( i - 1 ) + j ))
 VectorAddElementDV a_$i $j $value
 done
done

## Manually printing the two dimensional array ('a'):
echo "Printing the two-dimensional array 'a':"
if [ -n "$a_0" ]; then
 for ((i=1; i&lt;=$a_0; i++)); do
 eval current_vector_lenght=\$a\_$i\_0
 if [ -n "$current_vector_lenght" ]; then
 for ((j=1; j&lt;=$current_vector_lenght; j++)); do
 eval value=\"\$a\_$i\_$j\"
 printf "$value "
 done
 fi
 printf "\n"
 done
fi

################
### MAIN END ###
################
</code></pre>

blocks|key|320620|text|如果矩阵的每一行都是相同的大小，那么您可以简单地使用线性数组和乘法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|320621|那是,|320622|a=()
for+((+i=0;+i<4;+%2B%2Bi+));+do
++for+((+j=0;+j<5;+%2B%2Bj+));+do
+++++a[i*5%2Bj]=0
++done
done|code-block|syntax|javascript|320623|然后你的a[2][3]+=+3就变成了|offset|length|style|CODE|320624|a[2*5%2B3]+=+3|320625|这种方法可能值得转换为一组函数，但由于不能将数组传递给函数或从函数返回数组，因此必须使用按名称传递，有时还要使用eval。因此，我倾向于将多维数组放在“bash根本不打算做的事情”下。|320626|entityMap^0|0|0|0|4|B|0|0|1K|4|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|X|8|@$K|Y|L|Z|M|N]]|9|@]|A|$]]|$1|O|3|P|5|F|7|10|8|@]|9|@]|A|$G|H]]|$1|Q|3|R|5|6|7|11|8|@$K|12|L|13|M|N]]|9|@]|A|$]]|$1|S|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|T|$]]

If each row of the matrix is the same size, then you can simply use a linear array and multiplication.

That is,

<pre><code>a=()
for (( i=0; i&lt;4; ++i )); do
 for (( j=0; j&lt;5; ++j )); do
 a[i*5+j]=0
 done
done
</code></pre>

Then your <code>a[2][3] = 3</code> becomes 

<pre><code>a[2*5+3] = 3
</code></pre>

This approach might be worth turning into a set of functions, but since you can't pass arrays to or return arrays from functions, you would have to use pass-by-name and sometimes <code>eval</code>. So I tend to file multidimensional arrays under "things bash is simply Not Meant To Do".

blocks|key|320944|text|在bash中可以通过声明一维数组来实现二维数组，然后可以使用(r+*+col_size)+%2B+c)访问元素。下面的逻辑解开一维阵列(str_2d_arr)并打印为二维阵列。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|320945|col_size=3
str_2d_arr=()
str_2d_arr%2B=('abc'+'200'+'xyz')
str_2d_arr%2B=('def'+'300'+'ccc')
str_2d_arr%2B=('aaa'+'400'+'ddd')

echo+"Print+2D+array"
col_count=0
for+elem+in+${str_2d_arr[@]};+do
++++if+[+${col_count}+-eq+${col_size}+];+then
++++++++echo+""
++++++++col_count=0
++++fi
++++echo+-e+"$elem+\c"
++++((col_count%2B%2B))
done
echo+""|code-block|syntax|javascript|320946|输出为|320947|Print+2D+array
abc+200+xyz+
def+300+ccc
aaa+400+ddd|320948|下面的逻辑对于从上面声明的1D数组str_2d_arr中获取每一行非常有用。|320949|#+Get+nth+row+and+update+to+2nd+arg
get_row_n()
{
++++row=$1
++++local+-n+a=$2
++++start_idx=$((row+*+col_size))
++++for+((i+=+0;+i+<+${col_size};+i%2B%2B));+do
++++++++idx=$((start_idx+%2B+i))
++++++++a%2B=(${str_2d_arr[${idx}]})
++++done
}

arr=()
get_row_n+0+arr
echo+"Row+0"
for+e+in+${arr[@]};+do
++++echo+-e+"$e+\c"
done
echo+""|320950|320951|Row+0
abc+200+xyz|320952|entityMap^0|U|J|1U|A|0|0|0|0|H|A|0|0|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@$9|Y|A|Z|B|C]|$9|10|A|11|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|13|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|14|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|15|8|@$9|16|A|17|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|H|7|18|8|@]|D|@]|E|$I|J]]|$1|S|3|L|5|6|7|19|8|@]|D|@]|E|$]]|$1|T|3|U|5|H|7|1A|8|@]|D|@]|E|$I|J]]|$1|V|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]]|W|$]]

2D array can be achieved in bash by declaring 1D array and then elements can be accessed using <code>(r * col_size) + c)</code>. Below logic delcares 1D array (<code>str_2d_arr</code>) and prints as 2D array.

<pre><code>col_size=3
str_2d_arr=()
str_2d_arr+=('abc' '200' 'xyz')
str_2d_arr+=('def' '300' 'ccc')
str_2d_arr+=('aaa' '400' 'ddd')

echo "Print 2D array"
col_count=0
for elem in ${str_2d_arr[@]}; do
 if [ ${col_count} -eq ${col_size} ]; then
 echo ""
 col_count=0
 fi
 echo -e "$elem \c"
 ((col_count++))
done
echo ""
</code></pre>

Output is

<pre><code>Print 2D array
abc 200 xyz 
def 300 ccc
aaa 400 ddd
</code></pre>

Below logic is very useful to get each row from the above declared 1D array <code>str_2d_arr</code>.

<pre><code># Get nth row and update to 2nd arg
get_row_n()
{
 row=$1
 local -n a=$2
 start_idx=$((row * col_size))
 for ((i = 0; i &lt; ${col_size}; i++)); do
 idx=$((start_idx + i))
 a+=(${str_2d_arr[${idx}]})
 done
}

arr=()
get_row_n 0 arr
echo "Row 0"
for e in ${arr[@]}; do
 echo -e "$e \c"
done
echo ""
</code></pre>

Output is

<pre><code>Row 0
abc 200 xyz
</code></pre>

blocks|key|103624|text|可以简单地定义两个函数来写入($4是赋值)和读取具有任意名称($1)和索引($2和$3)的矩阵，利用eval和间接引用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|103625|#!/bin/bash

matrix_write+()+{
+eval+$1"_"$2"_"$3=$4
+#+aux=$1"_"$2"_"$3++++++++++#+Alternative+way
+#+let+$aux=$4+++++++++++++++#+---
}

matrix_read+()+{
+aux=$1"_"$2"_"$3
+echo+${!aux}
}

for+((i=1;i<10;i=i%2B1));+do
+for+((j=1;j<10;j=j%2B1));+do+
++matrix_write+a+$i+$j+$[$i*10%2B$j]
+done
done

for+((i=1;i<10;i=i%2B1));+do
+for+((j=1;j<10;j=j%2B1));+do+
++echo+"a_"$i"_"$j"="$(matrix_read+a+$i+$j)
+done
done|code-block|syntax|javascript|103626|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

One can simply define two functions to write ($4 is the assigned value) and read a matrix with arbitrary name ($1) and indexes ($2 and $3) exploiting eval and indirect referencing.

<pre><code>#!/bin/bash

matrix_write () {
 eval $1"_"$2"_"$3=$4
 # aux=$1"_"$2"_"$3 # Alternative way
 # let $aux=$4 # ---
}

matrix_read () {
 aux=$1"_"$2"_"$3
 echo ${!aux}
}

for ((i=1;i&lt;10;i=i+1)); do
 for ((j=1;j&lt;10;j=j+1)); do 
 matrix_write a $i $j $[$i*10+$j]
 done
done

for ((i=1;i&lt;10;i=i+1)); do
 for ((j=1;j&lt;10;j=j+1)); do 
 echo "a_"$i"_"$j"="$(matrix_read a $i $j)
 done
done
</code></pre>

blocks|key|103747|text|为了模拟一个二维数组，我首先加载前n个元素(第一列的元素)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|103748|local+pano_array=()++

i=0

for+line+in+$(grep++"filename"+"$file")
do+
++url=$(extract_url_from_xml+$line)
++pano_array[i]="$url"
++i=$((i%2B1))
done|code-block|syntax|javascript|103749|为了添加第二列，我定义了第一列的大小并计算偏移量变量中的值|103750|array_len="${#pano_array[@]}"

i=0

while+[[+$i+-lt+$array_len+]]
do
++url="${pano_array[$i]}"
++offset=$(($array_len%2Bi))+
++found_file=$(get_file+$url)
++pano_array[$offset]=$found_file

++i=$((i%2B1))
done|103751|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

For simulating a 2-dimensional array, I first load the first n-elements (the elements of the first column)

<pre><code>local pano_array=() 

i=0

for line in $(grep "filename" "$file")
do 
 url=$(extract_url_from_xml $line)
 pano_array[i]="$url"
 i=$((i+1))
done
</code></pre>

To add the second column, I define the size of the first column and calculate the values in an offset variable

<pre><code>array_len="${#pano_array[@]}"

i=0

while [[ $i -lt $array_len ]]
do
 url="${pano_array[$i]}"
 offset=$(($array_len+i)) 
 found_file=$(get_file $url)
 pano_array[$offset]=$found_file

 i=$((i+1))
done
</code></pre>

blocks|key|320765|text|Mark+Reed为二维数组(矩阵)提供了一个非常好的解决方案！它们总是可以转换为一维数组(向量)。尽管Bash没有对2D数组的原生支持，但围绕上述原则创建一个简单的ADT并不难。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|320766|下面是一个不带参数检查等的barebone示例，只是为了保持解决方案清晰:数组的大小被设置为实例中的前两个元素(实现矩阵ADT，https://github.com/vorakl/bash-libs/blob/master/src.docs/content/pages/matrix.rst的Bash模块的文档)|offset|length|320767|#!/bin/bash

matrix_init()+{
++++#+matrix_init+instance+x+y+data+...

++++declare+-n+self=$1++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++declare+-i+width=$2+height=$3++++++++++++++++++++++++++++++++++++++++++++++++
++++shift+3;++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

++++self=(${width}+${height}+"$@")+++++++++++++++++++++++++++++++++++++++++++++++
}+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

matrix_get()+{++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++#+matrix_get+instance+x+y

++++declare+-n+self=$1++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++declare+-i+x=$2+y=$3++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++declare+-i+width=${self[0]}+height=${self[1]}++++++++++++++++++++++++++++++++

++++echo+"${self[2%2By*width%2Bx]}"+++++++++++++++++++++++++++++++++++++++++++++++++
}+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

matrix_set()+{++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++#+matrix_set+instance+x+y+data

++++declare+-n+self=$1++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++declare+-i+x=$2+y=$3++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++declare+data="$4"+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++declare+-i+width=${self[0]}+height=${self[1]}++++++++++++++++++++++++++++++++

++++self[2%2By*width%2Bx]="${data}"+++++++++++++++++++++++++++++++++++++++++++++++++
}+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

matrix_destroy()+{+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++#+matrix_destroy+instance

++++declare+-n+self=$1++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++unset+self++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
}

#+my_matrix[3][2]=(+(one,+two,+three),+("1+1"+"2+2"+"3+3")+)
matrix_init+my_matrix+\+++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++++++3+2+\+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++++++one+two+three+\+++++++++++++++++++++++++++++++++++++++++++++++++++++
++++++++"1+1"+"2+2"+"3+3"

#+print+my_matrix[2][0]
matrix_get+my_matrix+2+0

#+print+my_matrix[1][1]
matrix_get+my_matrix+1+1

#+my_matrix[1][1]="4+4+4"
matrix_set+my_matrix+1+1+"4+4+4"++++++++++++++++++++++++++++++++++++++++++++++++

#+print+my_matrix[1][1]
matrix_get+my_matrix+1+1++++++++++++++++++++++++++++++++++++++++++++++++++++++++

#+remove+my_matrix
matrix_destroy+my_matrix|code-block|syntax|javascript|320768|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/vorakl/bash-libs/blob/master/src.docs/content/pages/matrix.rst^0|0|1S|29|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@$D|U|E|V|1|W]]|A|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

Mark Reed suggested a very good solution for 2D arrays (matrix)! They always can be converted in a 1D array (vector). Although Bash doesn't have a native support for 2D arrays, it's not that hard to create a simple ADT around the mentioned principle.

Here is a barebone example with no argument checks, etc, just to keep the solution clear: the array's size is set as two first elements in the instance (documentation for the Bash module that implements a matrix ADT, <a href="https://github.com/vorakl/bash-libs/blob/master/src.docs/content/pages/matrix.rst" rel="nofollow noreferrer">https://github.com/vorakl/bash-libs/blob/master/src.docs/content/pages/matrix.rst</a> )

<pre><code>#!/bin/bash

matrix_init() {
 # matrix_init instance x y data ...

 declare -n self=$1 
 declare -i width=$2 height=$3 
 shift 3; 

 self=(${width} ${height} "$@") 
} 

matrix_get() { 
 # matrix_get instance x y

 declare -n self=$1 
 declare -i x=$2 y=$3 
 declare -i width=${self[0]} height=${self[1]} 

 echo "${self[2+y*width+x]}" 
} 

matrix_set() { 
 # matrix_set instance x y data

 declare -n self=$1 
 declare -i x=$2 y=$3 
 declare data="$4" 
 declare -i width=${self[0]} height=${self[1]} 

 self[2+y*width+x]="${data}" 
} 

matrix_destroy() { 
 # matrix_destroy instance

 declare -n self=$1 
 unset self 
}

# my_matrix[3][2]=( (one, two, three), ("1 1" "2 2" "3 3") )
matrix_init my_matrix \ 
 3 2 \ 
 one two three \ 
 "1 1" "2 2" "3 3"

# print my_matrix[2][0]
matrix_get my_matrix 2 0

# print my_matrix[1][1]
matrix_get my_matrix 1 1

# my_matrix[1][1]="4 4 4"
matrix_set my_matrix 1 1 "4 4 4" 

# print my_matrix[1][1]
matrix_get my_matrix 1 1 

# remove my_matrix
matrix_destroy my_matrix
</code></pre>

blocks|key|103979|text|如果你在Mac上使用bash版本4，下面的代码肯定可以工作。你不仅可以声明0，而且这是一种更通用的动态接受值的方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|103980|二维数组|103981|declare+-A+arr
echo+"Enter+the+row"
read+r
echo+"Enter+the+column"
read+c
i=0
j=0
echo+"Enter+the+elements"
while+[+$i+-lt+$r+]
do
++j=0
++while+[+$j+-lt+$c+]
++do
++++echo+$i+$j
++++read+m
++++arr[${i},${j}]=$m
++++j=`expr+$j+%2B+1`
++done
++i=`expr+$i+%2B+1`
done

i=0
j=0
while+[+$i+-lt+$r+]
do
++j=0
++while+[+$j+-lt+$c+]
++do
++++echo+-n+${arr[${i},${j}]}+"+"
++++j=`expr+$j+%2B+1`
++done
++echo+""
++i=`expr+$i+%2B+1`
done|code-block|syntax|javascript|103982|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

The below code will definitely work provided if you are working on a Mac you have bash version 4. Not only can you declare 0 but this is more of a universal approach to dynamically accepting values.
<h1>2D Array</h1>
<pre><code>declare -A arr
echo &quot;Enter the row&quot;
read r
echo &quot;Enter the column&quot;
read c
i=0
j=0
echo &quot;Enter the elements&quot;
while [ $i -lt $r ]
do
 j=0
 while [ $j -lt $c ]
 do
 echo $i $j
 read m
 arr[${i},${j}]=$m
 j=`expr $j + 1`
 done
 i=`expr $i + 1`
done

i=0
j=0
while [ $i -lt $r ]
do
 j=0
 while [ $j -lt $c ]
 do
 echo -n ${arr[${i},${j}]} &quot; &quot;
 j=`expr $j + 1`
 done
 echo &quot;&quot;
 i=`expr $i + 1`
done
</code></pre>

I'm wondering how to declare a 2D array in bash and then initialize to 0.

In C it looks like this:

<pre><code>int a[4][5] = {0};
</code></pre>

And how do I assign a value to an element? As in C:

<pre><code>a[2][3] = 3;
</code></pre>

How to declare 2D array in bash

我想知道如何在bash中声明一个2D数组，然后初始化为0。在C中，它看起来像这样：int a[4][5] = {0};那么如何给元素赋值呢？与C中的一样：a[2][3] = 3;

问如何在bash中声明二维数组
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