PHP matches 6 to 16 character combinations (only numbers, letters, underscores)

PHP matches 6 to 16 bits of string.
Only 6 to 16 characters consisting of numbers, letters, and underscores are allowed, conforming to return ture, otherwise returning false.

Answer:
6 to 16 bits, the regular can be written like this: {6,16}.
A regular expression of any character 6 to 16 bits is this:. {6,16}
Only a combination of numbers, letters, and underscores is allowed, and the regular is: [0-9_a-za-z]

To integrate, the complete regular is:

^[_0-9a-z]{6,16}$

The following is an example of applying this regular validation password.

Php Auto-links:false; " ><?php/*** PHP Regular validation password rule * Allows only numbers, letters, underscores * Minimum 6-bit, maximum 16-bit * Collect collation: www.jbxue.com*/functionIspassword($STR) {if (Preg_match ('/^[_0-9a-z]{6,16}$/i ', $str)) {ReturnTrue }else {return FALSE;} $password =  ' [email protected] ';  if (Ispassword ($password)) {echo  ' compliant ';} else {echo  ' not compliant ';} //output does not conform to echo  ' <br> '; $ Password =  ' abcdeasdas_1324 ';  if (Ispassword ($password)) {echo  ' compliant ';} else {echo  ' not compliant ';} //output conforms to ?>        

PHP matches 6 to 16 character combinations (only numbers, letters, underscores)