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2025-04-02 Update From: SLTechnology News&Howtos shulou NAV: SLTechnology News&Howtos > Network Security >
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Shulou(Shulou.com)06/01 Report--
Variable: the memory space that stores a single element:
Array (multiple contiguous memory spaces): contiguous memory space that stores multiple elements:
Array name:
Index: numbering starts at 0 and belongs to numeric index
Note: indexes can also support custom formats, not just numeric formats:
The array of bash supports sparse format
Reference elements in the array: ${ARRAY_ name [index]}
Declare an array:
Declare-an ARRAY_NAME
Declare-An ARRAY_NAME: associative array: kv
Assignment of array elements:
(1) assign only one element at a time:
ARRAY_ name [index] = VALUE
# weekdays [0] = "Sunday"
# weekdays [4] = "Thursday"
(2) assign all elements at once:
ARRAY_NAME= ("VAL1", "VAL2", "VAL3",...)
(3) only specific elements are assigned:
ARRAY_NAME= ([0] = "VAL1" [3] = "VAL2"...)
(4) read-an ARRAY
Reference an element in the array:
${ARRAY_ name [index]}
Note: omitting [INDEX] indicates referencing the element with subscript 0
Show all elements in the array:
${ARRAY_NAME [*]}, or ${ARRAY_NAME [@]}
Count the length of the array (the number of elements in the array):
${# ARRAY_NAME [*]}, ${# ARRAY_NAME [@]}
Reference elements in an array:
Fetch all the elements in the array in turn: ${ARRAY [@]} or ${ARRAY [*]}
Array slices:
Take out the element of specified length in the array: ${ARRAY [@]: offset:number}: also called array slice
Offset: the number of elements to skip
Number: the number of elements to be taken out
Example: # echo ${weekdays [@]: 1:2}
All elements after the offset is taken out: ${ARRAY [@]: offset}
# echo ${weekdays [@]: 1}
Append elements to the array:
ARRAY [${# ARRAY [*]}]
Delete an element from the array:
Unset ARRAY [INDEX]
Associative array:
Declare-An ARRAY_NAME
ARRAY_NAME= ([index_name] = 'val1' [index_name2='val2'...])
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