true string length

mark_kccs

Hi to all

Is there a way to get the true/physical length of a string?

For example:
$str_m='mmmmmmmmmmmmmmmmmmmmmmmmmmmmmm';
$str_n='nnnnnnnnnnnnnnnnnnnnnnnnnnnnnn';
$str_i='iiiiiiiiiiiiiiiiiiiiiiiiiiiiii';

strlen() will of course show them all to be 30, but this is an actual character count. Would be great if anyone had an answer.

Many thanks.

bradgrafelman

The "physical length" of a string doesn't make sense... how do you measure the physical length of electric signals bouncing around inside of a computer?

Oh, did you mean the physical length of the displayed string? In that case, you'd first have to specify the exact font you want to measure the string in, since different fonts have different character widths.

After you do that, try looking at the [man]GD[/man] library - I believe there is a user-contributed note somewhere (might have to use Google to search the php.net manual) that attempts to estimate the physical length of text using GD.

dagon

so your asking "how long is a piece of sting?"

NogDog

Or just use a fixed-width font such as Courier, and they'll be the same length. 🙂

sneakyimp

The physical dimension of a string displayed in a browser can depend on a bazillion things -- the user's browser settings, the CSS styles applied, etc. You're going to have to be a lot more specific.

etully

If you are looking for the length, then you probably have a font and a rendering device in mind. I needed this once when I was positioning text on a graphic. (I wanted to position a word on the graphic so that the last letter was exactly ten pixels from the right hand side of the graphic).

I used ImageMagick for both jobs. First, you can pass it your string, font, font size (ie. 10 pt.) and attributes (italics, bold, etc), and ImageMagick will tell you how many pixels wide the string will be. (Then, in my case, I positioned the text at: $Width_Of_Graphic_In_Pixels - $Width_of_String - 10 ).

If you want something that is going to be correct no matter what browser, platform, or font the user might have, you're only going to succeed if you can ascertain the pixel width of each character in that font on that platform. Obviously, the browser knows this information (for rendering purposes) at a very low level but I doubt that that information is made available to Javascript. I wonder if you could position the text in a div or span and then query the div or span for its width? Never tried it. That's where I'd look first.

sneakyimp

etully! long time no see.

I also doubt that the actual string or character dimensions are available to Javascript. I have seen hacks where one can estimate the length of a string based on an index -- the index being a rough approximation of average character's pixel dimensions or perhaps the widest character's dimensions.