数组基础 Shell 脚本 |设置 2（使用循环）

建议通过Array Basics Shell Scripting |组 1
介绍
假设您想多次重复特定任务，那么最好使用循环。大多数语言都提供循环的概念。在 Bourne Shell 中有两种类型的循环，即for循环和
while循环。

在 Bash 中打印静态数组

1.通过使用while循环

${#arr[@]}用于查找 Array 的大小。

# !/bin/bash
# To declare static Array 
arr=(1 12 31 4 5)
i=0
  
# Loop upto size of array
# starting from index, i=0
while [ $i -lt ${#arr[@]} ]
do
    # To print index, ith
    # element
    echo ${arr[$i]}
      
    # Increment the i = i + 1
    i=`expr $i + 1`
done

输出：

1
2
3
4
5

2. 使用for循环

# !/bin/bash
# To declare static Array 
arr=(1 2 3 4 5)
  
# loops iterate through a 
# set of values until the
# list (arr) is exhausted
for i in "${arr[@]}"
do
    # access each element 
    # as $i
    echo $i
done

输出：

1
2
3
4
5

在运行时读取数组元素，然后打印数组。

1.使用While循环

# !/bin/bash
# To input array at run
# time by using while-loop
  
# echo -n is used to print
# message without new line
echo -n "Enter the Total numbers :"
read n
echo "Enter numbers :"
i=0
  
# Read upto the size of 
# given array starting from
# index, i=0
while [ $i -lt $n ]
do
    # To input from user
    read a[$i]
  
    # Increment the i = i + 1
    i=`expr $i + 1`
done
  
# To print array values 
# starting from index, i=0
echo "Output :"
i=0
  
while [ $i -lt $n ]
do
    echo ${a[$i]}
  
    # To increment index
    # by 1, i=i+1 
    i=`expr $i + 1`
done

输出：

Enter the Total numbers :3
Enter numbers :
1
3
5
Output :
1
3
5

2.使用for循环

# !/bin/bash
# To input array at run 
# time by using for-loop
  
echo -n "Enter the Total numbers :"
read n
echo "Enter numbers:"
i=0
  
# Read upto the size of 
# given array starting 
# from index, i=0
while [ $i -lt $n ]
do
    # To input from user
    read a[$i]
  
    # To increment index 
    # by 1, i=i+1
    i=`expr $i + 1`
done
  
# Print the array starting
# from index, i=0
echo "Output :"
  
for i in "${a[@]}"
do
    # access each element as $i
    echo $i 
done

输出：

Enter the Total numbers :3
Enter numbers :
1
3
5
Output :
1
3
5