PHP : Strings - [1.7] Controlling Case

1.7.1 Problem

You need to capitalize, lowercase, or otherwise modify the case of letters in a string. For example, you want to capitalize the initial letters of names but lowercase the rest.

1.7.2 Solution

Use ucfirst( ) or ucwords( ) to capitalize the first letter of one or more words:

print ucfirst("how do you do today?");
print ucwords("the prince of wales");
How do you do today?
The Prince Of Wales

Use strtolower( ) or strtoupper( ) to modify the case of entire strings:

print strtoupper("i'm not yelling!");
// Tags must be lowercase to be XHTML compliant
print strtolower('<A HREF="one.php">one</A>');
I'M NOT YELLING!
<a href="one.php">one</a>

1.7.3 Discussion

Use ucfirst( ) to capitalize the first character in a string:

print ucfirst('monkey face');
print ucfirst('1 monkey face');
Monkey face
1 monkey face

Note that the second line of output is not "1 Monkey face".

Use ucwords( ) to capitalize the first character of each word in a string:

print ucwords('1 monkey face');
print ucwords("don't play zone defense against the philadelphia 76-ers");
1 Monkey Face
Don't Play Zone Defense Against The Philadelphia 76-ers

As expected, ucwords( ) doesn't capitalize the "t" in "don't." But it also doesn't capitalize the "e" in "76-ers." For ucwords( ), a word is any sequence of nonwhitespace characters that follows one or more whitespace characters. Since both ' and - aren't whitespace characters, ucwords( ) doesn't consider the "t" in "don't" or the "e" in "76-ers" to be word-starting characters.

Both ucfirst( ) and ucwords( ) don't change the case of nonfirst letters:

print ucfirst('macWorld says I should get a iBook');
print ucwords('eTunaFish.com might buy itunaFish.Com!');
MacWorld says I should get a iBook
ETunaFish.com Might Buy ItunaFish.Com!

The functions strtolower( ) and strtoupper( ) work on entire strings, not just individual characters. All alphabetic characters are changed to lowercase by strtolower( ) and strtoupper( ) changes all alphabetic characters to uppercase:

print strtolower("I programmed the WOPR and the TRS-80.");
print strtoupper('"since feeling is first" is a poem by e. e. cummings.');
i programmed the wopr and the trs-80.
"SINCE FEELING IS FIRST" IS A POEM BY E. E. CUMMINGS.

When determining upper- and lowercase, these functions respect your locale settings.