我怎样才能使用php接受字母，数字，逗号（，）和点（。）

Question

I want to accept only letter, number, comma and dot using following regular expression. If i use $string it's saying invalid data but If i use $string2 it's saying valid data.

1) Why $string is not accepting as valid data ? anything I'm missing ?

2) If i accept comma then how can I escape it ? Using mysqli_real_escape_string ? If so then it's showing backslash when I showing it from Db. Please help. Thank You.

$string = "I m a good boy";
$string2 = "Imagoodboy";

if(preg_match("/^[a-zA-Z0-9]+$/", $string) == 0)
    echo "Invalid data";
else
    echo "Valid data";

Answer 1

You need to include . in your character class and reverse your if condition checks:

if(preg_match('/^[a-zA-Z0-9.]+$/', $string))
    echo "valid data";
else
    echo "InValid data";

Also $string has spaces also and space is not in your allowed character list that's why it is failing. If you want to include spaces also make regex as:

/^[a-zA-Z0-9. ]+$/

Answer 2

First String contain whitespace. According to your regular expression space is not valid.To validate $string you have to make valid whitespace in your regular expression.

Try this :

preg_match("/[^a-zA-Z0-9., ]/",$string);
                          ^
                        Space

Answer 3

I think the problem comes from spaces in your $string.

add a space in your capturing group

if(preg_match("/^[a-zA-Z0-9. ]+$/", $string) == 0)
    echo "Invalid data";
else
    echo "Valid data";

and it should work fine

DEMO

Answer 4

You missed a space and . , try it:

if(preg_match("/^[\d\w\s\.]+$/", $string) == 0)
    echo "Invalid data";
else
    echo "Valid data";