PHP 5.2.x array Operation details sharing

$arr = Array ("a" = = 1, "b" = 2, "c" = 3); Copy Code If this defines an array, it will report a compilation error: $arr = Array ("A" = 1, "b" = 2, "c" = 3); Copy Code Therefore, when you define an array, you can only use the = 2, $arr = Array ("a" = = 1, "b" = 2, "c" = 3); echo $arr [0]; echo $arr [1]; Copy Code It was a blank shot. The correct way to print: echo $arr ["a"]; Copy Code 3, add elements or modify the elements can only use =, can not use = $arr = Array ("a" = = 1, "b" = 2, "c" = 3); $arr ["c"] = 6; Copy Code The above operation method, in PHP 5.2.5 will appear the compilation error Add elements or modify elements to write this: $arr = Array ("a" = = 1, "b" = 2, "c" = 3); $arr ["D"] = 4; $arr ["c"] = 6; Copy Code To delete an element, use unset: unset ($arr ["C"]); Copy Code 4, think of the following code, what will output? $arr = Array ("a" = =, "b" = 3,4); $arr [] = 5; foreach ($arr as $key = $value) { echo "Key: $key value: $value "; } Copy Code Output Result: $arr = Array ("a" = = 1,3, "b" = 2); After the array is created, the default pointer refers to the first element Echo current ($arr). " "; Move forward a position Echo Next ($arr). " "; The default rule for grooming is small to large Sort ($arr); After finishing the array pointer again stops at the first element Echo current ($arr). " "; Echo Next ($arr). " "; Back one position Echo prev ($arr). " "; Copy Code Output results: 13121

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