PHP pack, unpack, Ord function using method (binary stream Interface application example) go

PHP pack, unpack, Ord function using method (binary stream Interface application example) Blog Category:

• Php

PHP binary Packunpackord in the work, I also gradually learned that Pack,unpack,ord is powerful for binary byte processing. Let me introduce them to you. In our work, there is not much estimation of their use. I am in a recent job, because the communication needs to use the binary stream, and then the interface is received in PHP. At that time, a lot of information was consulted. Because they are really less used, they are seldom used by friends in their work. At work, I also learned that Pack,unpack,ord is powerful for binary byte processing. Let me introduce them to you.
Pacrk function Description: This function is used to compress data into a string in place.


Syntax: Pack (format,args+)

Parameter description
Format required. Specifies the format to use when wrapping the data.
Args+ is optional. Specifies one or more parameters that are packaged.


Character description
A fills the string blank with a NULL character
A fills the string blanks with space characters (spaces)
H 16 string, low in front
H 16 string, high in front
C with number characters
C No number character
S has a short integer (16 bits, depending on the computer's bit order)
S no-number short integer (16 bits, depending on the computer's bit order)
n unsigned short integers (16-bit, high-order in the back)
V Short Integer (16 bits, low in the back order)
I number integers (depending on the computer's order and range)
I no-number integers (depending on the computer's order and range)
L number Long Integer (32 bits, depending on the computer's bit order)
L unsigned long integers (32 bits, depending on the computer's bit order)
N unsigned short integers (32-bit, high-order in the back)
V short Integer (32 bits, low in the back order)
F Single precision floating point number (depending on the range of the computer)
D-times accurate floating point number (depending on the computer's range)
X vacancy
X Rewind One
@ Fill in NULL characters to absolute position


Unpack function Description: This function is used to extract the data of the bit string

Syntax: Unpack (format,args+)

Parameter description
Format required. Specifies the format to use when wrapping the data.
Args+ is optional. Specifies one or more parameters that are packaged.

The parameters are the same as the pack.

Ord function Description: Returns the Acill code value of the corresponding character

Syntax: Ord ($character);


Example Description:
PHP code

2. A character
4. $str = (Pack ( "A *", "China"));
6. Echo $str, "=", strlen ( $str), "byte \ n";
8. Getascill ( $str);
10. echo ' <br/> ';
14. H character
16. $str = (Pack ( "h*", "Fffe"));
18. Echo $str, "=", strlen ( $str), "byte \ n";
20. Getascill ( $str);
22. echo ' <br/> ';
26. C character
28. $str = (Pack ( "c*", "n", "57") ;
30. Echo $str, "=", strlen ( $str), "byte \ n";
32. Getascill ( $str);
34. echo ' <br/> ';
38. I-character short-shaped 32-bit 4-byte 64-bit 8-byte
40. $str = (Pack ( "i", "100"));
42. Echo $str, "=", strlen ( $str), "byte \ n";
44. Getascill ( $str);
46. echo ' <br/> ';
50. s character short shaping 2 bytes
52. $str = (Pack ( "s", "100"));
54. Echo $str, "=", strlen ( $str), "byte \ n";
56. Getascill ( $str);
58. echo ' <br/> ';
62. L character-length shaping 4 bytes
64. $str = (Pack ( "L", "100"));
66. Echo $str, "=", strlen ( $str), "byte \ n";
68. Getascill ( $str);
70. echo ' <br/> ';
74. F-character single-precision floating-point 4 bytes
76. $str = (Pack ( "F", "100"));
78. Echo $str, "=", strlen ( $str), "byte \ n";
80. Getascill ( $str);
82. echo ' <br/> ';
86. D-character double-precision floating-point 8 bytes
88. $str = (Pack ( "D", "100"));
90. Echo $str, "=", strlen ( $str), "byte \ n";
92. Getascill ( $str);
94. echo ' <br/> ';
98. function Getascill ($str) {
100. $arr = str_split ( $str);
102. foreach ( $arr as $v) {
104. echo $v, "=", Ord ( $v), "\ n";
106. }
108. echo "=============\r\n\r\n";
110. }

With the above example, we can see that the same string, stored in a different format, consumes a different number of bytes. It can also be seen here that saving characters in different formats can save space for storage. and start the unreadable encryption effect. Suddenly think of a bit, Design database field type problems, if a field is just: 10-bit length integer type. We set it to reshape: 256*256*256*256 is 4 bytes, if set to 10 length string. That accounts for 10 bytes. The whole digestive space is twice times the size. Setting the correct character type is a great help in improving database performance. Oh, a little off-topic ...




A case analysis of PHP processing byte code communication
Just said pack function: space-saving, encrypted format

Here are 2 examples to illustrate, interface development requirements:


Parameter description
User name 20 bytes, character type
Password 10 bytes, character type
Age 1 Bytes, no character char type
Date of birth 4 bytes, integer (19800101)
Mailbox 50 Bytes, string
Between fields: "\" split
A, pack Packaging

PHP code

2. $code =Array (
6. "username" = =Array ("A20","Zhang San adfb12"),
10. "Pass" =Array ("A10","asdf* #1"),
14. "Age" = =Array ("C", "All"),
18. "Birthday" = =Array ("I","19900101"),
22. "Email" = =Array ("A50","[email protected]"));
26. $stream =join ("n", Packbyarr ($code));
30. Echo $stream,strlen ($stream);
40. File_put_contents ("C:/1.txt",$stream); //Save the stream for easy reading below.
48. function Packbyarr ($arr) {
52. $ATARR =Array ();
56. foreach ($arr as $k = =$v) {
60. $ATARR []=pack ($v [0],$v [1]);
64. }
68. return $ATARR;
72. }
76. function Getascill ($str) {
80. $arr =str_split ($str);
84. foreach ($arr as $v) {
88. echo $v,"=", Ord ($v),"\ n";
92. }
96. }

The entire length is 89 bytes, because it is split with "\". With the above output, some string output can be read, the others have become garbled. This is what I said can be kept secret effect reason.

B, unpack unpacking
The unpacking needs to be read in a packaged manner, the length of the read, what type to read, and the same as the packing rules.

PHP code

2. $code =Array (
6. "username" = =Array ("A20"),
10. "Pass" =Array ("A10"),
14. "Age" = =Array ("C"),
18. "Birthday" = =Array ("I"),
22. "Email" = =Array ("A50"));
26. $stream =file_get_contents ("C:/1.txt");
30. Var_dump (Packbyarr ($stream,$code));
34. function Packbyarr ($str,$code) {
38. $ARR =explode ("n",$str);
42. $ATARR =Array ();
46. $i = 0;
50. foreach ($code as $k = =$v) {
54. $ATARR [$k]=unpack ($v [0],$Arr [$i]);
58. $i + +;
62. }
66. return $ATARR;
70. }

Citation: http://randomclan.blog.163.com/blog/static/1453009820125454418912/