Php implements hexadecimal conversion (binary, octal, and hexadecimal) to implement code conversion.

Convert decimal to binary, octal, and hexadecimal
To convert from decimal to other hexadecimal values, the number is used to continuously divide by the number of hexadecimal values to be converted and read the remainder. Connect them together.
Copy codeThe Code is as follows:
<? Php
/**
* Convert decimal to binary, octal, or hexadecimal with zero padding before the digits being insufficient *
*
* @ Param array $ datalist input data array (100,123,130)
* @ Param int $ bin conversion can be: 2, 8, 16
* @ Return array returns the data array () and returns the format in which no data is converted.
* @ Copyright chengmo QQ: 8292669
*/
Function decto_bin ($ datalist, $ bin)
{
Static $ arr = array (, 'A', 'B', 'C', 'D', 'E ', 'F ');
If (! Is_array ($ datalist) $ datalist = array ($ datalist );
If ($ bin = 10) return $ datalist; // ignore in the same hexadecimal format
$ Bytelen = ceil (16/$ bin); // obtain the length of a byte in $ bin notation.
$ AOutChar = array ();
Foreach ($ datalist as $ num)
{
$ T = "";
$ Num = intval ($ num );
If ($ num = 0) continue;
While ($ num> 0)
{
$ T = $ arr [$ num % $ bin]. $ t;
$ Num = floor ($ num/$ bin );
}
$ Tlen = strlen ($ t );
If ($ tlen % $ bytelen! = 0)
{
$ Pad_len = $ bytelen-$ tlen % $ bytelen;
$ T = str_pad ("", $ pad_len, "0", STR_PAD_LEFT). $ t; // The length of less than one byte is automatically increased to 0.
}
$ AOutChar [] = $ t;
}
Return $ aOutChar;
}

Test:
Var_dump (decto_bin (array (128,253), 2 ));
Var_dump (decto_bin (array (128,253), 8 ));
Var_dump (decto_bin (array (128,253), 16 ));

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Array (2 ){
[0] =>
String (8) "10000000"
[1] =>
String (8) "11111101"
}
Array (2 ){
[0] =>
String (4) 0200"
[1] =>
String (4) 0375"
}
Array (2 ){
[0] =>
String (2) "80"
[1] =>
String (2) "FD"
}
Binary, octal, and hexadecimal to decimal
This conversion uses multiplication, for example: 1101 to decimal: 1*2 ^ 3 + 1*2 ^ 2 + 0*2 ^ 1 + 1*2 ^ 0
Code:

Copy codeThe Code is as follows:
<? Php
/**
* Convert binary, octal, and hexadecimal to decimal *
*
* @ Param array $ datalist input data array (df, ef)
* @ Param int $ bin conversion can be: 2, 8, 16
* @ Return array returns the data array () and returns the format in which no data is converted.
* @ Copyright chengmo QQ: 8292669
*/
Function bin_todec ($ datalist, $ bin)
{
Static $ arr = array ('0' => 0, '1' => 1, '2' => 2, '3' => 3, '4' => 4, '5' => 5, '6' => 6, '7' => 7, '8' => 8, '9' => 9, 'A' => 10, 'B' => 11, 'c' => 12, 'D' => 13, 'E' => 14, 'F' => 15 );
If (! Is_array ($ datalist) $ datalist = array ($ datalist );
If ($ bin = 10) return $ datalist; // do not convert to the 10th hexadecimal format
$ AOutData = array (); // defines the output to save the array
Foreach ($ datalist as $ num)
{
$ Atnum = str_split ($ num); // splits the string into a single character array.
$ Atlen = count ($ atnum );
$ Total = 0;
$ I = 1;
Foreach ($ atnum as $ TV)
{
$ TV = strtoupper ($ TV );
If (array_key_exists ($ TV, $ arr ))
{
If ($ arr [$ TV] = 0) continue;
$ Total = $ total + $ arr [$ TV] * pow ($ bin, $ atlen-$ I );
}
$ I ++;
}
$ AOutData [] = $ total;
}
Return $ aOutData;
}

Test:
Var_dump (bin_todec (array ('ff ', 'ff33', 'cc33'), 16 ));
Var_dump (bin_todec (array ('20140901', '20160901'), 2 ));
Var_dump (bin_todec (array ('20140901', '20160901'), 8 ));

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Array (3 ){
[0] =>
Int (255)
[1] =>
Int (65331)
[2] =>
Int (52275)
}
Array (2 ){
[0] =>
Int (124)
[1] =>
Int (508)
}
Array (2 ){
[0] =>
Int (342099)
[1] =>
Int (5345)
}
Later, these are just implementation methods. In fact, they do not care about php or other languages, and the Implementation ideas are the same. Php actually has many built-in functions to accomplish this:
Bindec (), decoct (), dechex () base_convert () decbin () is just the implementation idea here. Haha!