How PHP determines if an array is indexed

Example to detect if the PHP array is an indexed array. function Is_assoc ($arr) { Return Array_keys ($arr)!== range (0, COUNT ($arr)-1); Array_values ($arr)!== $arr } function Is_assoc2 ($array) { Return (BOOL) count (Array_filter (Array_keys ($array), ' is_string ')); } $array = Array (0=> "1",1=> "3"); Var_dump ($array); echo Is_assoc ($array)? ' Indexed array ': ' is not an indexed array '; echo " "; echo is_assoc2 ($array)? ' Indexed array ': ' is not an indexed array '; echo " "; $array = Array ("0" = "1", "1" = "3"); Var_dump ($array); echo Is_assoc ($array)? ' Indexed array ': ' is not an indexed array '; echo " "; echo is_assoc2 ($array)? ' Indexed array ': ' is not an indexed array '; echo " "; $array = Array ("name" = "1", "Age" = "3"); Var_dump ($array); echo Is_assoc ($array)? ' Indexed array ': ' is not an indexed array '; echo " "; echo is_assoc2 ($array)? ' Indexed array ': ' is not an indexed array '; Copy Code Output: Array (size=2) 0 = string ' 1 ' (length=1) 1 = = String ' 3 ' (length=1) not an indexed array is not an indexed array (size=2) 0 = string ' 1 ' (length=1) 1 = String ' 3 ' (length=1) not an indexed array is not an indexed array (size=2) ' name ' = = String ' 1 ' (length=1) ' age ' = Stri Ng ' 3 ' (length=1) indexed array of index arrays

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