PHP implements various sorting algorithms

// Bubble sort
function BubbleSort($arr) {
// Get the total length of the array
$num = count($arr);
// Forward traversal of the array
for ($i = 1; $i $num; $i++ ) {
// Reverse traversal
for ($j = $num - 1; $j >= $ i ; $j--) {
// Compare two adjacent numbers
if ($arr[$j] $arr[$j -1]) {
// Temporarily store smaller numbers
$iTemp = $arr[$j-1];
// Put the bigger ones in front
$arr[$j-1] = $arr[$j ];
//Put the smaller one at the back
$arr[$j] = $iTemp;
}
}
}
return $arr;
}

// Exchange sorting
function ExchangeSort($arr){
$num = count($arr);
// Traverse the array
for ($i = 0;$i $num - 1 ; $i++) {
// Get the next index of the current index
for ($j = $i + 1; $j $num ; $j++) {
//Compare the values ​​of two adjacent ones
if ($arr[$j] $arr[$i ]) {
// Temporarily store smaller numbers
$iTemp = $arr[$i];
// Put the bigger ones in front
$arr[$i] = $arr[$j];
//Put the smaller one at the back
$arr[$j] = $iTemp;
}
}
}
return $arr;
}

//Selection sorting
function SelectSort($arr) {
// Get the total length of the array
$num = count($arr);
// Traverse the array
for ($i = 0;$i $num-1; $i++) {
// Temporarily store the current value
$iTemp = $arr[$i];
// Temporarily save the current location
$iPos = $i;
// Traverse the data after the current position
for ($j = $i + 1; $j $num ; $j++){
// If there is
less than the current value if ($arr[$j] $iTemp) {
// Temporary minimum value
$iTemp = $arr[$j];
// Temporary location
$iPos = $j;
}
}
// Put the current value into the calculated position
$arr[$iPos] = $arr[$i];
// Replace the current value with the calculated value
$arr[$i] = $iTemp;
}
return $arr;
}

// Insertion sorting
function InsertSort($arr){
$num = count($arr);
// Traverse the array
for ($i = 1;$i $num; $i++ ) {
// Get the current value
$iTemp = $arr[$i];
// Get the previous position of the current value
$iPos = $i - 1;
//If the current value is less than the previous value, it has not reached the beginning of the array
while (($iPos >= 0) && ($iTemp $arr[ $iPos])) {
// Put the previous value one digit back
$arr[$iPos