An in-depth understanding of the PHP array count function _php instance

Count ()

The PHP count () function calculates the number of cells in an array or the number of attributes in an object, returns the number of cells in an array, or the number of properties in an object.

Grammar:

int count (mixed var [, int mode]) if Var is a normal variable of an array, returns 1 and returns 0 for nonexistent, uninitialized, or empty arrays.

The optional parameter mode is set to Count_recursive (or 1) and count () is recursively counted, which is especially useful for all cells that compute multidimensional arrays, but count () does not recognize infinite recursion. The default value for mode is 0.

Example:

<?php
Echo Count ($x);      Output: 0
$a = 2;
echo count ($a);      Output: 1
$arr _age = Array (a);
echo Count ($arr _age);    Output: 3
?>

sizeof () is an alias for this function.

In practice, some loops are often performed based on the size of the array, and it is recommended that count () be written outside of the loop body:

<?php
$arr _age = Array (a);
$count = count ($arr _age);
For ($i =1 $i <= $count; $i + +) {
  echo "$i secondary loop";
}
? >

This does not have to perform the count () calculation every loop, of course this is not necessary.

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