You may not know this, but the latest version of PHP comes with avery powerful set of string manipulatation tools. This article takes anin-depth look at these tools and illustrates how they can save you time andeffort in your daily development activities.
If you're looking to perform a little cosmetic surgery on your strings, a good place to start is the family of trim() functions. The most useful of these, trim(), is constructed specifically to remove whitespace from the beginning and end of a string. This comes in handy if you need to remove whitespace from a value prior to using it elsewhere (a database insert, maybe?)
$str = " ever seen a white pigeon?";
// returns "ever seen a white pigeon?"
It's also a good idea to use the trim() function on data
entered into online forms, in order to ensure that your error-checking routines don't miss entries containing only whitespace. Here's an example which illustrates what I mean:
$search = " ";
// bad code, will not identify that search string
// actually contains nothing
if ($search != "")
// good code, will account for whitespace-only entries
if (trim($search) != "")
You can also use the ltrim() and rtrim() functions, which
remove whitespace from the beginning and end of a string respectively.
The next few string functions come in very handy when adjusting the case of a text string from lower- to upper-case, or vice-versa:
strtolower() - convert string to lower case strtoupper()- convert string to upper case ucfirst() - convert the first character of string to upper case ucwords() - convert the first character of each word in string to upper case
Here's an example:
$str = "Something's rotten in the state of Denmark";
// returns "something's rotten in the state of denmark"
// returns "SOMETHING'S ROTTEN IN THE STATE OF DENMARK"
// returns "Something's rotten in the state of Denmark"
// returns "Something's Rotten In The State Of Denmark"
You've already used the print() function extensively to
display output. However, the print() function doesn't allow you to format output in any significant manner - for example, you can't write 1000 as 1,000 or 1 as 00001. And so the clever PHP developers came up with the sprintf() function, which allows you to define the format in which data is output.
Consider the following example:
// returns 1.6666666666667
As you might imagine, that's not very friendly. Ideally,
you'd like to display just the "significant digits" of the result. And so, you'd use the sprintf() function:
A quick word of explanation here: the PHP sprintf() function
is very similar to the printf() function that C programmers are used to. In order to format the output, you need to use "field templates", templates which represent the format you'd like to display.
Some common field templates are:
%s string %d decimal number %x hexadecimal number %o octal number %f float number
You can also combine these field templates with numbers which indicate the number of digits to display - for example, %1.2f implies that PHP should only display two digits after the decimal point. If you'd like the formatted string to have a minimum length, you can tell PHP which character to use for padding by prefixing it with a single quote (').
Here are a few more examples of sprintf() in action:
In addition to the sprintf() function, PHP also offers the
strpad() function, which is used for padding strings to a specific length. This function accepts a string or string variable as argument, together with the minimum string length required; a couple of optional arguments allow you to also specify which character to use for padding, and the direction in which padding is to take place.
Finally, the wordwrap() function can be used to break long
sentences at a specified length.
$str = "It's been ten years since Dr. Hannibal \"The Cannibal\" Lecter
(Anthony Hopkins) escaped from a maximum-security
penitentiary - ten years in which he's roamed free,
indulging his very specialized tastes. But out
of sight is very definitely not out of mind - he
still haunts Clarice Starling (Julianne Moore),
now a special agent in the FBI.";
// returns a word-wrapped block of width 50 characters
It's been ten years since Dr. Hannibal "The
Cannibal" Lecter (Anthony Hopkins) escaped from a
maximum-security penitentiary - ten years in which
he's roamed free, indulging his very specialized
tastes. But out of sight is very definitely not
out of mind - he still haunts Clarice Starling
(Julianne Moore), now a special agent in the FBI.
echo wordwrap($str, 50);