Several php pen-related questions by night passers-by _ PHP Tutorial

Several php pen questions from night travelers. I. Basic question 1. write the output result of the following program and copy the code as follows :? $ Str1null; $ str2false; echo $ str1 $ str2? Equal: not equal; $ str3; $ str40; ec I. basic questions
1. write the output results of the following program

The code is as follows:

$ Str1 = null;
$ Str2 = false;
Echo $ str1 = $ str2? 'Equality ': 'Unequal ';
$ Str3 = '';
$ Str4 = 0;
Echo $ str3 = $ str4? 'Equality ': 'Unequal ';
$ Str5 = 0;
$ Str6 = '0 ';
Echo $ str5 ===$ str6? 'Equality ': 'Unequal ';
?>

2. write the output results of the following program

The code is as follows:

$ A1 = null;
$ A2 = false;
$ A3 = 0;
$ A4 = '';
$ A5 = '0 ';
$ A6 = 'null ';
$ A7 = array ();
$ A8 = array ());
Echo empty ($ a1 )? 'True': 'false ';
Echo empty ($ a2 )? 'True': 'false ';
Echo empty ($ a3 )? 'True': 'false ';
Echo empty ($ a4 )? 'True': 'false ';
Echo empty ($ a5 )? 'True': 'false ';
Echo empty ($ a6 )? 'True': 'false ';
Echo empty ($ a7 )? 'True': 'false ';
Echo empty ($ a8 )? 'True': 'false ';
?>

3. write the output results of the following program

The code is as follows:

$ Test = 'aaaaa ';
$ Abc = & $ test;
Unset ($ test );
Echo $ abc;
?>

4. write the output results of the following program

The code is as follows:

Function get_count (){
Static $ count = 0;
Return $ count ++;
}
Echo $ count;
+ + $ Count;
Echo get_count ();
Echo get_count ();
?>

5. write the output results of the following program

The code is as follows:

$ GLOBALS ['var1'] = 5;
$ Var2 = 1;
Function get_value (){
Global $ var2;
$ Var1 = 0;
Return $ var2 ++;
}
Get_value ();
Echo $ var1;
Echo $ var2;
?>

6. write the output results of the following program

The code is as follows:

Function get_arr ($ arr ){
Unset ($ arr [0]);
}
$ Arr1 = array (1, 2 );
$ Arr2 = array (1, 2 );
Get_arr (& $ arr1 );
Get_arr ($ arr2 );
Echo count ($ arr1 );
Echo count ($ arr2 );
?>

7. get the extension of a file in more than five ways
Requirement: dir/upload.image.jpg to find. jpg or. jpg,
The PHP built-in handler must be used for processing. the methods cannot be repeated and can be encapsulated into functions, such as get_ext1 ($ file_name) and get_ext2 ($ file_name)
II. algorithm questions
1. use PHP to describe the bubble sort and quick sort algorithms. the object can be an array.
2. using PHP to describe sequential search and binary search (also called semi-query) algorithms, sequential search must take efficiency into account. the object can be an ordered array.
3. write a two-dimensional array sorting algorithm function that is universal and can call php built-in functions.
[Attached answer] (the answer below is not necessarily the best, but a simple reference)
I. basic questions
1. equal and unequal
2. true false
3. aaaaaa
4. 5 0 1
5. 5 2
6. 1 2
7. get the extension of a file in more than five ways

The code is as follows:

Function get_ext1 ($ file_name ){
Return strrchr ($ file_name ,'.');
}
Function get_ext2 ($ file_name ){
Return substr ($ file_name, strrpos ($ file_name ,'.'));
}
Function get_ext3 ($ file_name ){
Return array_pop (explode ('.', $ file_name ));
}
Function get_ext4 ($ file_name ){
$ P = pathinfo ($ file_name );
Return $ p ['extension'];
}
Function get_ext5 ($ file_name ){
Return strrev (substr (strrev ($ file_name), 0, strpos (strrev ($ file_name ),'.')));
}

II. algorithm questions
1. use PHP to describe the bubble sort and quick sort algorithms. the object can be an array.

The code is as follows:

// 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 quick_sort ($ 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 = quick_sort ($ left_arr );
$ Right_arr = quick_sort ($ right_arr );
Return array_merge ($ left_arr, array ($ key), $ right_arr );
}

2. use PHP to describe sequential search and binary search (also called semi-query) algorithms. efficiency must be considered for sequential search, and objects can be An ordered array

The code is as follows:

// 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;
}
// Sequential search (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;
}
}

3. write a two-dimensional array sorting algorithm function that is universal and can call php built-in functions.

The code is as follows:

// Two-dimensional array sorting. $ arr indicates data, $ keys indicates the key value of sorting, $ order indicates sorting rules, 1 indicates ascending, and 0 indicates descending.
Function array_sort ($ arr, $ keys, $ order = 0 ){
If (! Is_array ($ arr )){
Return false;
}
$ Keysvalue = array ();
Foreach ($ arr as $ key => $ val ){
$ Keysvalue [$ key] = $ val [$ keys];
}
If ($ order = 0 ){
Asort ($ keysvalue );
} Else {
Arsort ($ keysvalue );
}
Reset ($ keysvalue );
Foreach ($ keysvalue as $ key => $ vals ){
$ Keysort [$ key] = $ key;
}
$ New_array = array ();
Foreach ($ keysort as $ key => $ val ){
$ New_array [$ key] = $ arr [$ val];
}
Return $ new_array;
}

Example 1. write the following output code :? $ Str1 = null; $ str2 = false; echo $ str1 = $ str2? 'Equal ': 'Unequal'; $ str3 = ''; $ str4 = 0; ec...