Dynamic web skills PHP program string processing functions

// Simple decryption function (corresponding to the php_encrypt function) // simple encryption function (corresponding to the php_decrypt function) // simple decoding function (corresponding to the php_encode function) // simple encoding function (corresponding to the php_decode function) // Self-implemented string processing function

//------------------------
// 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 --){
$ Rev_str. = $ str [$ I];
}
Return $ rev_str;
}

// String matching
Function strcmp ($ s1, $ s2)
{
If (strlen ($ s1) <strlen ($ s2) return-1;
If (strlen ($ s1)> strlen ($ s2) return 1;
For ($ I = 0; $ I If ($ s1 [$ I] ==$ s2 [$ I]) {
Continue;
} Else {
Return false;
}
}
Return 0;
}

// Search for strings
Function strstr ($ str, $ substr)
{
$ M = strlen ($ str );
$ N = strlen ($ substr );
If ($ m <$ n) return false;
For ($ I = 0; $ I <= ($ m-$ n 1); $ I ){
$ Sub = substr ($ str, $ I, $ n );
If (strcmp ($ sub, $ substr) = 0) return $ I;
}
Return false;
}

// String replacement
Function str_replace ($ substr, $ newsubstr, $ str)
{
$ M = strlen ($ str );
$ N = strlen ($ substr );
$ X = strlen ($ newsubstr );
If (strchr ($ str, $ substr) = false) return false;

 

For ($ I = 0; $ I <= ($ m-$ n 1); $ I ){
$ I = strchr ($ str, $ substr );
$ Str = str_delete ($ str, $ I, $ n );
$ Str = str_insert ($ str, $ I, $ newstr );
}
Return $ str;
}
?>

//--------------------
// Self-implemented string processing functions
//--------------------

// Insert a string
Function str_insert ($ str, $ I, $ substr)
{
For ($ j = 0; $ j <$ I; $ j ){
$ Startstr. = $ str [$ j];
}
For ($ j = $ I; $ j $ Laststr. = $ str [$ j];
}
$ Str = ($ startstr. $ substr. $ laststr );
Return $ str;
}

// Delete a string
Function str_delete ($ str, $ I, $ j)
{
For ($ c = 0; $ c <$ I; $ c ){
$ Startstr. = $ str [$ c];
}
For ($ c = ($ I $ j); $ c $ Laststr. = $ str [$ c];
}
$ Str = ($ startstr. $ laststr );
Return $ str;
}

// Copy the string
Function strcpy ($ s1, $ s2)
{
If (strlen ($ s1) = NULL |! Isset ($ s2) return;
For ($ I = 0; $ I $ S2 [] = $ s1 [$ I];
}
Return $ s2;
}

// Connection string
Function strcat ($ s1, $ s2)
{
If (! Isset ($ s1) |! Isset ($ s2) return;
$ Newstr = $ s1;
For ($ I = 0; $ I $ Newstr. = $ st [$ I];

 

}
Return $ newsstr;
}

// Simple encoding function (corresponding to the php_decode function)
Function php_encode ($ str)
{
If ($ str = ''& strlen ($ str)> 128) return false;
For ($ I = 0; $ I $ C = ord ($ str [$ I]);
If ($ c> 31 & $ c <107) $ c = 20;
If ($ c> 106 & $ c <127) $ c-= 75;
$ Word = chr ($ c );
$ S. = $ word;
}
Return $ s;
}

// Simple decoding function (corresponding to the php_encode function)
Function php_decode ($ str)
{
If ($ str = ''& strlen ($ str)> 128) return false;
For ($ I = 0; $ I $ C = ord ($ word );
If ($ c> 106 & $ c <127) $ c = $ C-20;
If ($ c> 31 & $ c <107) $ c = $ c 75;
$ Word = chr ($ c );
$ S. = $ word;
}
Return $ s;
}

// Simple encryption function (corresponding to the php_decrypt function)
Function php_encrypt ($ str)
{
$ Encrypt_key = 'abcdefghijklmnopqrstuvwxyz1234567890 ';
$ Decrypt_key = 'ngzqtcobmuhelkpdawxfyivrsj2468038559 ';
If (strlen ($ str) = 0) return false;
For ($ I = 0; $ I For ($ j = 0; $ j If ($ str [$ I] ==$ encrypt_key [$ j]) {
$ Enstr. = $ decrypt_key [$ j];

 

Break;
}
}
}
Return $ enstr;
}

// Simple decryption function (corresponding to the php_encrypt function)
Function php_decrypt ($ str)
{
$ Encrypt_key = 'abcdefghijklmnopqrstuvwxyz1234567890 ';
$ Decrypt_key = 'ngzqtcobmuhelkpdawxfyivrsj2468038559 ';
If (strlen ($ str) = 0) return false;
For ($ I = 0; $ I For ($ j = 0; $ j If ($ str [$ I] ==$ decrypt_key [$ j]) {
$ Enstr. = $ encrypt_key [$ j];
Break;
}
}
}
Return $ enstr;
}
?>