Methods and details of array traversal in php (note)

Php array traversal method and details (note) // traverse the array

$ N = array (5, 7, 9, 1, 6, 2, 3 );

$ Sum = 0;

Echo"
Total ". count ($ n)." count
"; // Calculate the number of elements in the array

For ($ I = 0; $ I

{

Echo $ n [$ I];

$ Sum = $ sum + $ n [$ I];

}

Echo"
The total number is ". $ sum;

/*************************************** *************************/

// When an array is created, no subscript is specified for an element. php will automatically add a subscript (keyword) as the element with the largest subscript (integer)

$ Arr = array (5 => "logo", 567,580 );

Echo"
". $ Arr [5]; // The output value is the logo.

// $ Arr [5] = "yes"; replace the value of an element

Echo"
". $ Arr [6]; // The output value is 567.

Echo"
". $ Arr [7]."
"; // The output value is 580.

/*************************************** *************************/

$ Ar [true] = "hello"; // = $ ar [1]

$ Ar [false] = "word"; // = $ ar [0]

$ Ar [null] = "Hefei"; // = $ ar [""] null in php in many cases <=> ""

/*************************************** *************************/

// We can usually use print_r to display this array. var_dump provides more comprehensive information.

"
". Print_r ($ arr );

Echo"
";

"
". Var_dump ($ arr );

/*************************************** *************************/

$ Arra = array (2, 3 );

// Php arrays can be dynamically increased

$ Arra [2] = 56;

Echo"
". $ Arra [2];

/******************* Several important functions in php array ************ *********/

Echo"
The array length is ". count ($ n); // counts the number of arrays.

Echo"
";

Echo is_array ($ n); // determines whether the given variable is an array. if the returned value is 1, the others are false.

Echo"
";

Print_r ($ n); // display the array

Echo"
";

Var_dump ($ n); // display the array, including data types that are more comprehensive than print_r

Echo"
";

$ Str = "Shushan Baohe Yaohai Kaikai ";

$ S = explode ("", $ str); // used to split ("") and who ("$ str, after splitting, $ s is already an array.

Print_r ($ s );

Echo"
";

Echo is_array ($ s); // $ s is an array.

/******************* Array traversal method *************** ****************/

$ Colors = array ('red', 'blue', 'black', 'green', 'yellow ');

For ($ I = 0; $ I

{

Echo"
$ Colors [$ I] ";

}

Echo"
";

$ I = 0;

While ($ I

{

Echo"
$ Colors [$ I] ";

$ I ++;

}

Echo"
";

Foreach ($ colors as $ k => $ v)

{

Echo"
$ K = $ v ";

}

// Unset ($ colors [2]); delete array $ colors subscript 2 element subscript 2 after deletion the subscript will not move up to fill the gap