PHP is a regular judge can only enter alphabetic characters and digital examples

Digital Regular Filter

The code is as follows	Copy Code
if (Preg_match ("/^\d*$/", $yebihai)) Echo (' is a number '); Else Echo (' not number '); or use a function if (Is_numeric ($yebihai)) Echo (' is a number '); Else Echo (' not number ');

The difference between the two methods is that the Is_numeric decimal is also considered a number, and the decimal point is preceded by a character.

Regular expressions are the following numbers and letters:

The code is as follows	Copy Code
$password = ' ABC12 '; if (!preg_match (/^) ([a-z]+[0-9]+) | ( [0-9]+[a-z]+)] [a-z0-9]*$/i, $password)) { Echo ' Password must be a combination of numbers and letters '; }

If you want to limit the length of 6-15-bit English characters and numbers

As long as you add a strlen to judge the following $plen<6| | $plen >15

The code is as follows	Copy Code
$password = ' abc123 '; $plen =strlen ($password); if (!preg_match (/^) ([a-z]+[0-9]+) | ( [0-9]+[a-z]+)] [a-z0-9]*$/i, $password) | | $plen <6| | $plen >15) { Echo ' Password must be a combination of 6-15 digits and letters '; }

In fact, we can also use regular to limit the length

We can refer to the rules for length.

Verify the N-bit number: ^\d{n}$
Verify at least n digits: ^\d{n,}$
Verify the number of m-n bits: ^\d{m,n}$

The above is a number, we can combine the verification of just add a {} on it.

The code is as follows	Copy Code
$password = ' abc123 '; $plen =strlen ($password); if (!preg_match (/^) ([a-z]+[0-9]+) | ( [0-9]+[a-z]+)] [a-z0-9]*{8,}$/i, $password) | | $plen <6| | $plen >15) { Echo ' Password must be a combination of 8 digits and letters '; }

The length is 8 or more in fact, just add a {8 after the regular,} on it,