PHP sorting algorithm implementation code

These days are annoying and hard to learn. Randomly looked. Record this. The code is as follows:
// Function: PHP implements various sorting algorithms
// Author: windlike
// Datetime: 2007-06-09

// Bubble sort
Function BubbleSort ($ arr ){
$ Num = count ($ arr );
For ($ I = 1; $ I <$ num; $ I ++ ){
For ($ j = $ num-1; $ j >=$ I; $ j --){
If ($ arr [$ j] <$ arr [$ j-1]) {
$ ITemp = $ arr [$ j-1];
$ Arr [$ j-1] = $ arr [$ j];
$ Arr [$ j] = $ iTemp;
}
}
}
Return $ arr;
}

// Sort by exchange method
Function ExchangeSort ($ arr ){
$ Num = count ($ arr );
For ($ I = 0; $ I <$ num-1; $ I ++ ){
For ($ j = $ I + 1; $ j <$ num; $ j ++ ){
If ($ arr [$ j] <$ arr [$ I]) {
$ ITemp = $ arr [$ I];
$ Arr [$ I] = $ arr [$ j];
$ Arr [$ j] = $ iTemp;
}
}
}
Return $ arr;
}

// Sort by selection
Function SelectSort ($ arr ){
$ Num = count ($ arr );
For ($ I = 0; $ I <$ num-1; $ I ++ ){
$ ITemp = $ arr [$ I];
$ IPos = $ I;
For ($ j = $ I + 1; $ j <$ num; $ j ++ ){
If ($ arr [$ j] <$ iTemp ){
$ ITemp = $ arr [$ j];
$ IPos = $ j;
}
}
$ Arr [$ iPos] = $ arr [$ I];
$ Arr [$ I] = $ iTemp;
}
Return $ arr;
}

// Sort by insert
Function InsertSort ($ arr ){
$ Num = count ($ arr );
For ($ I = 1; $ I <$ num; $ I ++ ){
$ ITemp = $ arr [$ I];
$ IPos = $ I-1;
While ($ iPos> = 0) & ($ iTemp <$ arr [$ iPos]) {
$ Arr [$ iPos + 1] = $ arr [$ iPos];
$ IPos --;
}
$ Arr [$ iPos + 1] = $ iTemp;
}
Return $ arr;
}

// Quick sorting
Function QuickSort ($ arr ){
$ Num = count ($ arr );
$ L = $ r = 0;
For ($ I = 1; $ I <$ num; $ I ++ ){
If ($ arr [$ I] <$ arr [0]) {
$ Left [] = $ arr [$ I];
$ L ++;
} Else {
$ Right [] = $ arr [$ I];
$ R ++;
}
}
If ($ l> 1 ){
$ Left = QuickSort ($ left );
}
$ New_arr = $ left;
$ New_arr [] = $ arr [0];
If ($ r> 1 ){
$ Right = QuickSort ($ right );
}
For ($ I = 0; $ I <$ r; $ I ++ ){
$ New_arr [] = $ right [$ I];
}
Return $ new_arr;
}

$ Arr = array (7,1, 6,5, 2 );
$ Arr_new = QuickSort ($ arr );
Echo"

"; 
print_r($arr_new); 
echo "

";
?>