是字符集正则表达式

Question

I am working on a project where i have to validate the BECS characters. Bulk Electronic Clearing System (BECS) only allowed the following characters.

BECS Character set

Type                        Description
Numeric                     0 to 9
Alphabetic                  Uppercase A to Z and Lowercase a to z
+                           Plus sign
-                           Minus sign or hyphen
@                           At sign
SP                          Blank space
$                           Dollar sign
!                           Exclamation mark
%                           Percentage sign
&                           Ampersand
(                           Left Parenthesis
)                           Right Parenthesis
*                           Asterik
.                           Period or decimal point
/                           Solidus (slash)
#                           Number Sign (Pound or Hash)
=                           Equal Sign
:                           Colon
;                           Semicolon
?                           Question mark
,                           Comma
’                           Apostrophe
[                           Left square bracket
]                           Right square bracket
_                           Low line (underscore)
^                           Circumflex

I have tried the following but not working:

preg_match("/^[A-Za-z0-9^_[]',?;:=#/.*()&%!$ @+-]+$/", $string);

Answer 1

Inside character classes, you don't need to escape most of the metacharacters.

/^[A-Za-z0-9^_[\]',?;:=#\/.*()&%!$ @+-]+$/

• ] is escaped to prevent it from closing the character class
• / needs to be escaped because we're using it as regex delimiter
• - doesn't need to be escaped because it's the last character in the class
• ^ doesn't need to be escaped because it's not the first character in the class

Or, if you want a shorter expression, the following regex covers the same range:

/^[ !#-;=?-[\]^_a-z]+$/