我想知道如何在 bash 中声明一个二维数组,然后将其初始化为 0。在 C 中它看起来像这样:int a[4][5] = {0}; 以及如何为元素赋值?如在 C 中:a[2][3] = 3;
我想知道如何在 bash 中声明一个二维数组然后将其初始化为 0。
在 C 语言中它看起来像这样:
int a[4][5] = {0};
那么如何为元素赋值呢?例如在 C 中:
a[2][3] = 3;
在 bash 中模拟数组的一种方法(可以适应任意维数的数组):
#!/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 + 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 $1 on separate lines
local vector_length
vector_length=$(($1_0))
if [ "$vector_length" = "0" ]; then
echo "Vector \"$1\" is empty!"
else
echo "Vector \"$1\":"
for ((i=1; i<=$vector_length; i++)); 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<=$vector_length; i++)); do
unset $1_$i
done
unset $1_0
fi
}
##################
### MAIN START ###
##################
## Setting vector 'params' with all the parameters received by the script:
for ((i=1; i<=$#; 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<=$params_0; i++)); do
count=$((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<=$params2_0; i++)); do
eval current_elem_value=\"\$params2\_$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<=10; i++)); do
VectorAddElement a 0 i
for ((j=1; j<=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<=$a_0; i++)); do
eval current_vector_lenght=\$a\_$i\_0
if [ -n "$current_vector_lenght" ]; then
for ((j=1; j<=$current_vector_lenght; j++)); do
eval value=\"\$a\_$i\_$j\"
printf "$value "
done
fi
printf "\n"
done
fi
################
### MAIN END ###
################