# An example of array sequencing using PHP selection sequencing method _php techniques

Source: Internet
Author: User

In this paper, an example is given to analyze the method of selecting sorting by PHP. Share to everyone for your reference. The specific analysis is as follows:

The basic idea of choosing a sort method: direct use case to explain, for instance have an array \$arr = Array (2,6,3,9), from big to small sort.

The first large cycle: it first assumes that \$arr[0] is the maximum, and then compares it to \$arr[1]~ \$arr [3], if it is larger, then swaps, the process is this (2,6,3,9)---2 and 6---> (6,2,3,9)---6 and 3 than--- > (6,2,3,9)---6 and 9 ratio---> (9,2,3,6). Note that the subscript will also change here.

Second large cycle: assuming \$arr[1] maximum (excluding \$arr[0]), compared with \$arr[2]~ \$arr [3], the process is this (9,2,3,6)----2 and 3 ratio----> (9,3,2,6)---3 and 6---> ( 9,6,2,3).

The third big cycle: assuming \$arr[2] is the largest, compared to \$arr[3, the process is this (9,6,2,3)---2 and 3 ratio---> (9,6,3,2)

The same, after the N-1 of the large cycle, you can arrange out

The PHP code is as follows, which is also encapsulated with functions

```<?php
function Selectsort (& \$arr) {for
(\$i =0; \$i <count (\$arr); \$i + +) {
\$max = \$arr [\$i];
for (\$j = \$i +1; \$j <count (\$arr); \$j + +) {
if (\$max < \$arr [\$j]) {
\$max = \$arr [\$j];
\$arr [\$j] = \$arr [\$i];
\$arr [\$i] = \$max;
}
}} return \$arr;
}
\$myarr = Array (2,6,3,9);
Selectsort (\$myarr);
echo "<pre>";
Print_r (\$myarr);
? >```

Code Analysis:

The first big cycle:

\$i =0 Array (2,6,3,9)
\$j = 1, perform 2 and 6 ratios: Become \$arr[0]=6, \$arr [1]=2, \$max =6 namely (6,2,3,9)
\$j = 2, performing 3 and 6 ratios: not executing
\$j = 3, perform 9 and 6 ratios: Become \$arr[0]=9, \$arr [3]=6, \$max =9 namely (9,2,3,6)

Second big cycle:

\$i =1, \$max = \$arr [1]=2, Array (9,2,3,6)
\$j = 2, perform 3 and 2 ratios: Become \$arr[1]=3, \$arr [2]=2, \$max =3 namely (9,3,2,6)
\$j = 3, perform 6 and 3 ratios: Become \$arr[1]=6, \$arr [3]=3, \$max =6 namely (9,6,2,3)

The third big cycle:

\$i =2, \$max = \$arr [2]=2, Array (9,6,2,3)
\$j = 3, perform 3 and 2 ratios: Become \$max[2]=3, \$arr [3]=2, \$max =3 namely (9,6,3,2)

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