Introduction to PHP arrays
Array Basics: In PHP, the subscript of an array can be an integer or a string in PHP, and the order of elements in an array is not determined by the subscript, but is defined by the order in which it "joins": $arr 1 = Array (element 1, Element 2, ...). ); Array (1,1.1,5, ' abc ', TRUE,FALSE); can store any data at this time as the default subscript array (2=>1,4=>1.1,3=>5,7=> ' abc ', 0=>TRUE); Subscript can be arbitrarily set (no order, no continuous) array (2=>1,1.1,1=>5, ' abc ', 0=>TRUE); You can add subscript, or do not add the subscript is the default subscript//default subscript rule: The largest number of previous used subscript +1//The number subscript is: 2,3,1,4,0 Array (2=>1, ' dd ' =>5,1=>1.1, ' abc ' , 0=>true); Mix subscript, also follow the default subscript rule array ( -2=>1, ' dd ' =>5,1.1, ' abc ', TRUE); The negative subscript is not counted in the integer subscript, but only as the word Poute//Then the subscript of the last three items of this array is: 0,1,2 Array (2.7=>1, ' dd ' =>5,1=>1.1, ' abc ', TRUE); Floating-point bidding clubs are automatically converted to integers, and the fractional part of the array ("2.7" =>1, ' dd ' =>5, ' one ' =>1.1, ' abc ', true) is removed directly; A pure numeric string subscript, treated as a number array (2=>1, ' dd ' =>5,true=>1.1, ' abc ', FALSE=>TRUE); Boolean value as subscript, true for 1,false is 0 array (2=>1, ' dd ' =>5,2=>1.1, ' abc ', TRUE); If the subscript is repeated with the preceding, then the other form of the underlying value with the same name is covered simply: $arr 1[] = 1; $arr 1[] = 5; $arr 1[] = 1.1; ...//directly after the variable is used [], it becomes an array, and in turn assigns a value $arr 2[' AA '] = 1; $arr 2[' bb '] = 5; $arr 2[5] = 1.1; ...//This form of subscript, in fact, with the use of the array syntax structure almost the same as the classification of arrays: from the key value relationship is divided into: Associative arrays: an example of an array that typically refers to the subscript as a string, and that string can roughly express the meaning of the data: $person = Array ("name" = "Poe", "Age" = "edu" = "University Graduate"); Indexed array: usually refers to an array of subscript strict 0-based continuous digital subscript-like the JS array from the array hierarchy: a one-dimensional array: is an array of each element value, is a normal value (non-array value) Example: $person = Array ("name" and "=" Poe "," Age "," edu "=" University Graduate "); Two-dimensional arrays: Each item in an array is another one-dimensional array. $person = Array ("name" = = Array ("Xiaohua", "Xiaofang"), "age" = = Array (18,22), "edu" = = Array ("University graduate", "primary School",)); Multidimensional arrays: In turn ... The general syntactic form of multidimensional arrays: $v 1 = array name [subscript] [subscript] [...] array traversal: Traversal basic Syntax: foreach ($arr as [$key =>] $value) {//$key and $value can be all possible Operations--because they are a variable//$key represents the subscript for each element that is obtained, either a number or a string//$value represents the value of each acquisition element, possibly various types//this loop structure will traverse from the first item of the array to the last item and then end} Array pointers and traversal principles: each array has a "pointer" inside it, which determines the element that is taken when the array is currently taking the value, which is dependent on the pointer during the foreach traversal. Example: $arr 1 = Array (2=>1, ' dd ' =>5,1=>1.1, ' abc ', 0=>TRUE); The wkiol1znx1sxflt6aaanrltn90q498.jpg pointer is in addition to the position setting for the Foreach loop, and some other functions depend on the pointer: 1: $v 1 = current ($arr 1); Gets the value of the element that the current pointer points to in $ARR1, or false2 If no element is pointed to: $v 1 = key ($arr 1); Gets the subscript of the element that the current pointer points to in the $ARR1, ... 3: $v 1 = Next ($arr 1); Move the pointer to the next element and get the value of the next element 4: $v 1 = prev ($arr 1); Move the pointer to the previous element and get the value of the previous element 5: $v 1 = reset ($arr 1); Move the pointer to "first element" and get the value of the element 6: $v 1 = end ($arr 1); Move the pointer to the last element and get the value of the element 7: $v 1 = each ($arr 1); Gets the subscript and value of the current element, and then moves the pointer to the next position
http://www.bkjia.com/PHPjc/1073352.html www.bkjia.com true http://www.bkjia.com/PHPjc/1073352.html techarticle PHP Arrays Introduce the basics of arrays: in PHP, the subscript of an array can be an integer, or it can be a string in PHP, and the order of elements in an array is not determined by the subscript, but by the order in which it is added ...
