CODEWITHSUNDEEP
phpregexvalidation
user12378334
user12378334

Reputation: 117

Regex for Input Validation in PHP

I need a Regex to accept the input only following possible cases like

1.It start with characters only [a-zA-Z]

2.It may contains numbers but it may not repeated 3 or moretimes.

Example:

akjsjdfljsfjl133113 Valid

123123sfsf not valid

asfsdf1111asdf notvalid adf111 not valid

I have tried this code

$input_line="sfjs123232";
preg_match("/^[a-zA-Z](\d)\1{2,}/", $input_line, $output_array);

Upvotes: 3

Views: 757

Answers (1)

hwnd
hwnd

Reputation: 70722

You can use a Negative Lookahead here.

^[a-zA-Z]+(?:(?!.*(\d)\1{2,}).)*$

See Live demo

Regular expression

^                the beginning of the string
[a-zA-Z]+        any character of: 'a' to 'z', 'A' to 'Z' (1 or more times)
(?:              group, but do not capture (0 or more times)
 (?!             look ahead to see if there is not:
  .*             any character except \n (0 or more times)
  (              group and capture to \1:
   \d            digits (0-9)
  )              end of \1
   \1{2,}        what was matched by capture \1 (at least 2 times)
  )              end of look-ahead
  .              any character except \n
 )*              end of grouping
$                before an optional \n, and the end of the string

Upvotes: 4

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