bash 在 Linux shell 脚本中，如何打印数组的最大值和最小值？
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In Linux shell script how do i print the largest and smallest values of a array?
提问by BobbyT28
I dont really understand much about arrays but i need to know how to find and print the largest and smallest values of an array. The array is predefined by a read command, the user will be prompted to enter n amount of integers.
我不太了解数组，但我需要知道如何查找和打印数组的最大值和最小值。该数组由读取命令预定义，用户将被提示输入 n 个整数。
How would i assign the read input to an array and find and display the largest and smallest values of the array?
我如何将读取输入分配给数组并查找并显示数组的最大值和最小值？
Is there a way to test the array elements to see if they are all integers?
有没有办法测试数组元素以查看它们是否都是整数？
#!/bin/bash
read -a integers
biggest=${integers[0]}
smallest=${integers[0]}
for i in ${integers[@]}
do
if [[ $i -gt $biggest ]]
then
biggest="$i"
fi
if [[ $i -lt $smallest ]]
then
smallest="$i"
fi
done
echo "The largest number is $biggest"
echo "The smallest number is $smallest"
回答by sampson-chen
The general idea is to iterate through the array once and keep track of what the maxand minseen so far at each step.
一般的想法是遍历数组一次并跟踪每一步到目前为止看到的max和min看到的内容。
Some comments and explanations in-line (prefixed by #)
一些评论和解释（以 为前缀#）
# This is how to declare / initialize an array:
arrayName=(1 2 3 4 5 6 7)
# Use choose first element of array as initial values for min/max;
# (Defensive programming) - this is a language-agnostic 'gotcha' when
# finding min/max ;)
max=${arrayName[0]}
min=${arrayName[0]}
# Loop through all elements in the array
for i in "${arrayName[@]}"
do
# Update max if applicable
if [[ "$i" -gt "$max" ]]; then
max="$i"
fi
# Update min if applicable
if [[ "$i" -lt "$min" ]]; then
min="$i"
fi
done
# Output results:
echo "Max is: $max"
echo "Min is: $min"
回答by Gilles Quenot
Try this if you need to compare(signed or not) INTegers:
如果您需要比较（签名与否）INTegers ，请尝试此操作：
#!/bin/bash
arr=( -10 1 2 3 4 5 )
min=0 max=0
for i in ${arr[@]}; do
(( $i > max || max == 0)) && max=$i
(( $i < min || min == 0)) && min=$i
done
echo "min=$min
max=$max"
OUTPUT
输出
min=-10
max=5
EXPLANATIONS
说明
arr=( )is the declaration of the array((...))is an arithmetic command, which returns an exit status of 0 if the expression is nonzero, or 1 if the expression is zero. Also used as a synonym for "let", if side effects (assignments) are needed. See http://mywiki.wooledge.org/ArithmeticExpression[[is a bash keyword similar to (but more powerful than) the[command. See http://mywiki.wooledge.org/BashFAQ/031and http://mywiki.wooledge.org/BashGuide/TestsAndConditionalsUnless you're writing for POSIX sh, we recommend[[foo || barruns bar when foo fails:[[ -d $foo ]] || { echo 'ohNoes!' >&2; exit 1; }cmd1 && cmd2: cmd1 is executed, and then if its exit status was 0 (true), cmd2 is executed. See http://mywiki.wooledge.org/BashGuide/TestsAndConditionals
arr=( )是数组的声明((...))是一个算术命令，如果表达式不为零，则返回退出状态 0，如果表达式为零，则返回 1。如果需要副作用（赋值），也用作“let”的同义词。见http://mywiki.wooledge.org/ArithmeticExpression[[是一个 bash 关键字，类似于（但比[命令更强大）。请参阅http://mywiki.wooledge.org/BashFAQ/031和http://mywiki.wooledge.org/BashGuide/TestsAndConditionals除非您为 POSIX sh 编写，否则我们建议您[[foo || bar当 foo 失败时运行 bar：[[ -d $foo ]] || { echo 'ohNoes!' >&2; exit 1; }cmd1 && cmd2: cmd1 被执行，然后如果其退出状态为 0 (true)，则 cmd2 被执行。请参阅http://mywiki.wooledge.org/BashGuide/TestsAndConditionals
回答by gniourf_gniourf
A funny way using sort:
使用排序的一种有趣方式：
if you have an array of integers, you can use sortto sort it, then select the first and last elements to have the min and max elements, as in:
如果你有一个整数数组，你可以用sort它来排序，然后选择第一个和最后一个元素来包含最小和最大元素，如下所示：
{ read min; max=$(tail -n1); } < <(printf "%s\n" "${array[@]}" | sort -n)
So if you want to prompt user for say 10 integers, check that the user entered integers and then sort them, you could do:
因此，如果您想提示用户输入 10 个整数，请检查用户是否输入了整数，然后对它们进行排序，您可以这样做：
#!/bin/bash
n=10
array=()
while ((n));do
read -p "[$n] Give me an integer: " i
[[ $i =~ ^[+-]?[[:digit:]]+$ ]] || continue
array+=($i)
((--n))
done
# Sort the array:
{ read min; max=$(tail -n1); } < <(printf "%s\n" "${array[@]}" | sort -n)
# print min and max elements:
echo "min=$min"
echo "max=$max"
