PHP code: basic data structure and php built-in functions

// -------------------- // Basic data structure // ---------------------- // binary search (find an element in the array) functionbin_sch ($ array, $ low, $ high, $ k) {if ($ low $ high) {$ midintval ($ low + $ high)

//--------------------
// Basic data structure
//--------------------

// Binary search (find an element in the array)
Function bin_sch ($ array, $ low, $ high, $ k ){
If ($ low <= $ high ){
$ Mid = intval ($ low $ high)/2 );
If ($ array [$ mid] === k ){
Return $ mid;
} Elseif ($ k <$ array [$ mid]) {
Return bin_sch ($ array, $ low, $ mid-1, $ k );
} Else {
Return bin_sch ($ array, $ mid 1, $ high, $ k );
}
}
Return-1;
}

// Search in sequence (find an element in the array)
Function seq_sch ($ array, $ n, $ k ){
$ Array [$ n] = $ k;
For ($ I = 0; $ I <$ n; $ I ){
If ($ array [$ I] === k ){
Break;
}
}
If ($ I <$ n ){
Return $ I;
} Else {
Return-1;
}
}

// Delete a linear table (implemented in an array)
Function delete_array_element ($ array, $ I)
{
$ Len = count ($ array );
For ($ j = $ I; $ j <$ len; $ j ){
$ Array [$ j] = $ array [$ j 1];
}
Array_pop ($ array );
Return $ array;
}

// Bubble sort (array sorting)
Function bubble_sort ($ array)
{
$ Count = count ($ array );
If ($ count <= 0) return false;
For ($ I = 0; $ I <$ count; $ I ){
For ($ j = $ count-1; $ j> $ I; $ j --){
If ($ array [$ j] <$ array [$ j-1]) {
$ Tmp = $ array [$ j];
$ Array [$ j] = $ array [$ j-1];
$ Array [$ j-1] = $ tmp;
}
}
}
Return $ array;
}

// Fast sorting (array sorting)
Function quicksort ($ array ){
If (count ($ array) <= 1) return $ array;
$ Key = $ array [0];
$ Left_arr = array ();
$ Right_arr = array ();
For ($ I = 1; $ I If ($ array [$ I] <= $ key)
$ Left_arr [] = $ array [$ I];
Else
$ Right_arr [] = $ array [$ I];
}
$ Left_arr = quicksort ($ left_arr );
$ Right_arr = quicksort ($ right_arr );
Return array_merge ($ left_arr, array ($ key), $ right_arr );
}

//------------------------
// PHP built-in string function implementation
//------------------------

// String length
Function strlen ($ str)
{
If ($ str = '') return 0;
$ Count = 0;
While (1 ){
If ($ str [$ count]! = NULL ){
$ Count;
Continue;
} Else {
Break;
}
}
Return $ count;
}

// Truncate the substring
Function substr ($ str, $ start, $ length = NULL)
{
If ($ str = ''| $ start> strlen ($ str) return;
If ($ length! = NULL) & ($ start> 0) & ($ length> strlen ($ str)-$ start) return;
If ($ length! = NULL) & ($ start <0) & ($ length> strlen ($ str) $ start) return;
If ($ length = NULL) $ length = (strlen ($ str)-$ start );
If ($ start <0 ){
For ($ I = (strlen ($ str) $ start); $ I <(strlen ($ str) $ start $ length); $ I ){
$ Substr. = $ str [$ I];
}
}
If ($ length> 0 ){
For ($ I = $ start; $ I <($ start $ length); $ I ){
$ Substr. = $ str [$ I];
}
}
If ($ length <0 ){
For ($ I = $ start; $ I <(strlen ($ str) $ length); $ I ){
$ Substr. = $ str [$ I];
}
}
Return $ substr;
}

// String flip
Function strrev ($ str)
{
If ($ str = '') return 0;
For ($ I = (strlen ($ str)-1); $ I> = 0; $ I --){