php regex filename

Question

Hi, anyone can help me with a preg_match? I'd like to use php's preg_match to determine if an input is a valid filename or not (only the filename + file extension, not the full path). General rules:

1) filename = a-z, A-Z, 0-9
2) extension = 3 or 4 letters

Thank you!

Answer 1

Try this:

preg_match('/^[a-zA-Z0-9]+\.[a-zA-Z]{3,4}$/', $filename)

Answer 2

/^[a-zA-Z0-9]+\.[a-zA-Z]{3,4}$/

If you want to enforce min/max length for the file name part:

//minimum 4 characters and a maximum of 8 characters

/^[a-zA-Z0-9]{4,8}\.[a-zA-Z]{3,4}$/

Answer 3

^\w+\.\w{3,4}$

Should work.

Answer 4

You can do:

if(preg_match('#^[a-z0-9]+\.[a-z]{3,4}$#i',$filename)) {
        echo "Valid";
}else{
        echo "not Valid";
}