Summary of some methods for randomly generating strings in php

Mt_rand function

Example

In this example, we will return some random numbers:

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<? Php Echo (mt_rand ()); Echo (mt_rand ()); Echo (mt_rand (10,100 )); ?> The output is similar: 3150906288 513289678 35

Let's take a look at the mt_rand function instance.

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Function roll (){ Return mt_rand (1, 6 ); } Echo roll (); Function roll ($ sides ){ Return mt_rand (1, $ sides ); } Echo roll (6); // roll a six-sided die Echo roll (10); // roll a ten-sided die Echo roll (20); // roll a twenty-sided die

All of the above can only generate simple numbers, not letters, numbers, and letters. Now we need to use a user-defined function.

The code is as follows:

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<? Php Function genRandomString ($ len ){ $ Chars = array ( "A", "B", "c", "d", "e", "f", "g", "h", "I", "j ", "k ", "L", "m", "n", "o", "p", "q", "r", "s", "t", "u ", "v ", "W", "x", "y", "z", "A", "B", "C", "D", "E", "F ", "G ", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q ", "R ", "S", "T", "U", "V", "W", "X", "Y", "Z", "0", "1 ", "2 ", "3", "4", "5", "6", "7", "8", "9" ); $ CharsLen = count ($ chars)-1; Shuffle ($ chars); // disrupt the array     $ Output = ""; For ($ I = 0; $ I <$ len; $ I ++ ){ $ Output. = $ chars [mt_rand (0, $ charsLen)];     }     Return $ output; } $ Str = genRandomString (25 ); $ Str. = "<br/> "; $ Str. = genRandomString (25 ); $ Str. = "<br/> "; $ Str. = genRandomString (25 ); $ Str. = "<br/> "; Echo $ str; ?> The program output is as follows: DmLVAmDkEJz8wHXRCNwzvANlB BILZSA19YyuSVcR17KrrZsOKO InlWlQF0GSabN3l589y9s16Gg

Example

The default length of a random string is 5. The generated string contains digits and uppercase letters.

Function:

1. Generate a random string of the specified length

2. Flexible selection of the complexity of the generated random string

The code is as follows:

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/** + ---------------------------------------------------------- * Generate random strings + ---------------------------------------------------------- * @ Param int $ length the length of the random string to be generated * @ Param string $ type random code type: 0, number + upper-case letter; 1, Number; 2, lower-case letter; 3, upper-case letter; 4, Special character;-1, numbers + uppercase/lowercase letters + Special characters + ---------------------------------------------------------- * @ Return string + ---------------------------------------------------------- */ Function randCode ($ length = 5, $ type = 0 ){ $ Arr = array (1 => "0123456789", 2 => "abcdefghijklmnopqrstuvwxyz", 3 => "ABCDEFGHIJKLMNOPQRSTUVWXYZ", 4 => "~ @ # $ % ^ & * () {} [] | "); If ($ type = 0 ){ Array_pop ($ arr ); $ String = implode (",", $ arr ); } Else if ($ type = "-1 "){ $ String = implode (",", $ arr ); } Else { $ String = $ arr [$ type];     } $ Count = strlen ($ string)-1; For ($ I = 0; $ I <$ length; $ I ++ ){ $ Str [$ I] = $ string [rand (0, $ count)]; $ Code. = $ str [$ I];     } Return $ code; }

Example

1. Preset a character array $ chars, including A-z, a-Z, 0-9, and some special characters
2. Use array_rand () to randomly select $ length elements from the array $ chars.
3. Extract the string from the array $ chars based on the obtained key name array $ keys. The disadvantage of this method is that the same characters are not repeated.

The code is as follows:

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Function make_password ($ length = 8) { // Password character set, which can be any character you need $ Chars = array ('A', 'B', 'C', 'D', 'e', 'F', 'G', 'H ', 'I', 'J', 'K', 'L', 'M', 'n', 'O', 'P', 'Q', 'R ','s ', 'T', 'u', 'V', 'W', 'X', 'y', 'z', 'A', 'B', 'C ', 'D ', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'n ', 'o ', 'P', 'Q', 'R','s ', 'T', 'u', 'V', 'W', 'X', 'y ', 'Z ', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9 ', '! ', '@', '#', '$', '%', '^ ','&','*','(',')','-', '_', '[', ']', '{', '}', '<', '> ','~ ', ''',' + ',' = ',',', '.',';',':','/','? ',' | '); // Random $ length array element key names in $ chars $ Keys = array_rand ($ chars, $ length ); $ Password = ''; For ($ I = 0; $ I <$ length; $ I ++)     { // Concatenate $ length array elements into strings $ Password. = $ chars [$ keys [$ I];     } Return $ password; }