bash 迭代并替换数组中的元素
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Iterate over and replace element in array
提问by nhershy
I am trying to replace the word "Apples" with "Cantaloupe" in my 'copy' array. What I am doing now is not throwing errors, but no change occurs in the copy array.
我试图在我的“副本”数组中用“哈密瓜”替换“苹果”这个词。我现在所做的不是抛出错误，而是复制数组中没有发生任何变化。
#!/bin/bash
fruits=("Oranges" "Apples" "Bananas" "Grapes")
echo "Original list:"
echo "${fruits[@]}"
copy=("${fruits[@]}")
for i in ${copy[@]}
do
if [[ copy[$i] == "Apples" ]]; then
copy[$i]="Canteloupe"
fi
done
echo "Copied list:"
echo "${copy[@]}"
My output:
我的输出：
Original list:
Oranges Apples Bananas Grapes
Copied list:
Oranges Apples Bananas Grapes
采纳答案by Inian
In your original approach you are looping over the keysin the array using which you would not be able to get the index of that element to replace.
在您的原始方法中，您正在循环使用数组中的键，您将无法获取要替换的元素的索引。
You need to change to modify the logic to loop over indicesof the array as
您需要更改以修改逻辑以循环数组的索引作为
for i in "${!copy[@]}"; do
if [[ ${copy[$i]} == "Apples" ]]; then
copy[$i]="Canteloupe"
fi
done
should solve your problem.
应该可以解决您的问题。
The construct for i in "${!copy[@]}"; dois for looping with indices of the array starting from 0to size of the array which lets you to replace the element in the index where you find the required string.
该构造for i in "${!copy[@]}"; do用于循环使用数组的索引，从数组的0大小开始，这使您可以替换索引中找到所需字符串的元素。
Expanding the answer to point out the difference when using either of array iteration ways.
扩展答案以指出使用任何一种数组迭代方式时的差异。
Looping over indices
循环索引
for i in "${!copy[@]}"; do
printf "%s\t%s\n" "$i" "${copy[$i]}"
done
prints
印刷
0 Oranges
1 Apples
2 Bananas
3 Grapes
and over keys
和过键
for i in "${copy[@]}"; do
printf "%s\n" "$i"
done
produces,
产生，
Oranges
Apples
Bananas
Grapes
回答by Sergey Shevchenko
The solution explained in the accepted answer to this similar questionmight be preferable:
在这个类似问题的公认答案中解释的解决方案可能更可取：
array=("${array[@]/Apples/Canteloupe}")
array=("${array[@]/Apples/Canteloupe}")
This depends on your general attitude towards Bash trickery. In technical terms, there are no downsides to manually iterating over the elements.
这取决于您对 Bash 诡计的总体态度。从技术角度来说，手动迭代元素没有任何缺点。
