Converting first letters to capital letters (uppercase) - PHP. Php case change functions convert string to uppercase function

IN PHP variables and constant names are case sensitive, but function names are not.

As far as I know, PHP is the only language that does this. All other languages ​​I've used are either completely case sensitive or completely case insensitive.

Why PHP partially refers to sensitive?

Please note that I'm not asking which names are case sensitive, but Why .

Case sensitive

• variables
• constants
• array keys
• class properties
• class constants

Case insensitive(both user defined and PHP)

• functions
• class constructors
• class methods
• keywords and constructs (if, else, null, foreach, echo, etc.)

basics

Variables in PHP are represented by a dollar sign followed by the variable name. The variable name is case sensitive.

Variable names follow the same rules as other labels in PHP. A valid variable name begins with a letter or underscore, followed by any number of letters, numbers, or underscores. As regular expression it is expressed as follows: "*"

1. User Guide for Users
2. Why are functions and methods in PHP case insensitive?
3. Are PHP functions case sensitive?
4. Are PHP keywords case sensitive?
5. Are the names PHP functions case sensitive or not?
6. Source of PHP Sensitivity

Delicate case

variables, constants, array keys, class properties, class constants

Case insensitive

functions, class constructors, class methods, keywords and constructs (if, else, null, foreach, echo, etc.),

For file names:

Note that case sensitivity also depends on your environment.

When you develop something on your WAMP or XAMPP it will be case insensitive when you change to Linux server it will throw an error.

Why is PHP partly sensitive?

I can only assume that this is due to the very earlier versions maybe with PHP/FI 2.0. The manual clearly states:

Please be aware that PHP/FI function names are not case sensitive.

Most user data such as GET parameters and POST were always registered as global variables. Treating these questions as case-insensitive would likely have caused problems, which is presumably why all variables were treated as case-sensitive.

From what I can tell, these were the only identifier types in PHP/FI 2.0. All the others were introduced later, apparently imitating case-insensitive function names.

Constants, which are special, were only introduced with PHP 4 (the PHP 3 manual mentions "constants", but these days they are called "literals"). For some mysterious reason (perhaps no consensus could be found), the decision was made to allow persistent identifiers to define() d to be either case-sensitive or insensitive to developer rejection. It's interesting to note that while define() uses case-sensitive constants by default, the corresponding C copy (REGISTER_*_CONSTANT) is case-insensitive by default.

Converts characters in a string to lower case.

Syntax:

String strtolower(string str);

Converts a string to lowercase. Returns the result of the translation.

It should be noted that if the locale is incorrectly configured, the function will produce, to put it mildly, strange results when working with Cyrillic letters.

$str = "HeLLo World"; $str = strtolower($str); echo $str; // prints hello world

strtoupper

Converts the given string to uppercase.

Syntax:

String strtoupper(string str);

Converts the string to upper case. Returns the result of the conversion. This function works well with English letters, but can be weird with Russian ones.

$str = "Hello World"; $str = strtoupper($str); echo $str; // will print HELLO WORLD

ucfirst

Converts the first character of a string to uppercase.

Syntax:

String ucfirst(string str);

Returns a string whose first character is uppercase.

$str = "hello world"; $str = ucfirst($str); echo $str; // prints Hello world

ucwords

Converts the first character of each word in a string to uppercase.

Syntax:

String ucwords(string str);

Returns a string in which the first character of each word in the string is capitalized.

A word here refers to a section of a line preceded by a white space character: space, new line, page feed, carriage return, horizontal and vertical tab.

Cyrillic characters may not be converted correctly.

$str = "hello world"; $str = ucfirst($str); echo $str; // prints Hello World

PHP is good for its variety of native language functions. However, in some cases it is necessary to add missing functionality. This is especially noticeable when working with string conversion functions and various encodings.

For example, ucfirst is a function that converts the first character of a string to uppercase. It would seem that no problems should arise, but when working with Cyrillic, such a conversion does not occur. This also applies to the ucwords function - it converts the first character of each word in a line to uppercase.

There are no problems with the characters of the English alphabet:

"; //converts the first character of each word in the line to uppercase echo ucwords($str); ?>

Test string Test String

But there are problems with the Cyrillic alphabet:

"; //converts the first character of each word in the line to uppercase echo ucwords($str); ?>

Test line test line

For PHP, cases are typical when functions work “poorly” or do not work at all with Cyrillic. Some functions with the mb prefix solve problems with the Cyrillic alphabet. For example, mb_strtolower - converts a string to lowercase. Unlike strtolower(), whether a character is a letter is determined based on the properties of the Unicode character.

To solve the problem, let's define a function mb_ucfirst(string str [, string encoding]), which will process Unicode characters.

To convert the first character of each word in a line to uppercase, just use mb_convert_case in the MB_CASE_TITLE mode.

11 years ago

Note that mb_strtolower() is very SLOW, if you have a database connection, you may want to use it to convert your strings to lower cases. Even latin1/9 (iso-8859-1/15) and other encodings are possible.

Have a look at my simple benchmark:

$text = "Lörem ipßüm dölör ßit ämet, cönßectetüer ädipißcing elit. Sed ligülä. Präeßent jüßtö tellüß, grävidä eü, tempüß ä, mättiß nön, örci. m qüiß lörem. venenätiß jüßtö. ßtie. önüllä.";

// mb_strtolower()
$timeMB = microtime(true);

For($i = 0 ; $i< 30000 ; $i ++)
$lower = mb_strtolower("$text/no-cache-$i");

$timeMB = microtime(true) - $timeMB;

// MySQL lower()
$timeSQL = microtime(true);

Mysql_query("set names latin1");
for($i = 0 ; $i< 30000 ; $i ++) {
$r = mysql_fetch_row(mysql_query("select lower(" $text /no-cache- $i ")" ));
$lower = $r [ 0 ];
}

$timeSQL = microtime(true) - $timeSQL;

echo "mb: " . sprintf ("%.5f" , $timeMB ). "sec.
" ;
echo "sql: " . sprintf ("%.5f" , $timeSQL ). "sec.
" ;

// Result on my notebook:
// mb: 11.50642 sek.
// sql: 5.44143 sek.

?>

7 years ago

Please, note that when using with UTF-8 mb_strtolower will only convert upper case characters to lower case which are marked with the Unicode property "Upper case letter" ("Lu"). However, there are also letters such as "Letter numbers" (Unicode property "Nl") that also have lower case and upper case variants. These characters will not be converted be mb_strtolower!

Example:
The Roman letters Ⅰ, Ⅱ, Ⅲ, ..., Ⅿ (UTF-8 code points 8544 through 8559) also exist in their respective lower case variants ⅰ, ⅱ, ⅲ, ..., ⅿ (UTF-8 code points 8560 through 8575) and should, in my opinion, also be converted by mb_strtolower, but they are not!

Big internet-companies (like Google) do match both variants as semantically equal (since the representations only differ in case).

Since I was not finding any proper solution in the internet on how to map all UTF8-strings to their lowercase counterpart in PHP, I offer the following hard-coded extended mb_strtolower function for UTF-8 strings:

The function wraps the existing function mb_strtolower() and additionally replaces uppercase UTF8-characters for which there is a lowercase representation. Since there is no proper Unicode uppercase and lowercase character-table in the internet that I was able to find, I checked the first million UTF8-characters against the Google-search and -KeywordTool and identified the following 78 characters as uppercase-characters, not being replaced by mb_strtolower, but having a UTF8 lowercase counterpart.

//the numbers in the in-line-comments display the characters" Unicode code-points (CP).
function strtolower_utf8_extended ($utf8_string)
{
$additional_replacements = array
("Dž" => "dž" // 453 -> 454
, "Lj" => "lj" // 456 -> 457
, "Nj" => "nj" // 459 -> 460
, "Dz" => "dz" // 498 -> 499
, "Ϸ" => "ϸ" // 1015 -> 1016
, "Ϲ" => "ϲ" // 1017 -> 1010
, "Ϻ" => "ϻ" // 1018 -> 1019
, "ᾈ" => "ᾀ" // 8072 -> 8064
, "ᾉ" => "ᾁ" // 8073 -> 8065
, "ᾊ" => "ᾂ" // 8074 -> 8066
, "ᾋ" => "ᾃ" // 8075 -> 8067
, "ᾌ" => "ᾄ" // 8076 -> 8068
, "ᾍ" => "ᾅ" // 8077 -> 8069
, "ᾎ" => "ᾆ" // 8078 -> 8070
, "ᾏ" => "ᾇ" // 8079 -> 8071
, "ᾘ" => "ᾐ" // 8088 -> 8080
, "ᾙ" => "ᾑ" // 8089 -> 8081
, "ᾚ" => "ᾒ" // 8090 -> 8082
, "ᾛ" => "ᾓ" // 8091 -> 8083
, "ᾜ" => "ᾔ" // 8092 -> 8084
, "ᾝ" => "ᾕ" // 8093 -> 8085
, "ᾞ" => "ᾖ" // 8094 -> 8086
, "ᾟ" => "ᾗ" // 8095 -> 8087
, "ᾨ" => "ᾠ" // 8104 -> 8096
, "ᾩ" => "ᾡ" // 8105 -> 8097
, "ᾪ" => "ᾢ" // 8106 -> 8098
, "ᾫ" => "ᾣ" // 8107 -> 8099
, "ᾬ" => "ᾤ" // 8108 -> 8100
, "ᾭ" => "ᾥ" // 8109 -> 8101
, "ᾮ" => "ᾦ" // 8110 -> 8102
, "ᾯ" => "ᾧ" // 8111 -> 8103
, "ᾼ" => "ᾳ" // 8124 -> 8115
, "ῌ" => "ῃ" // 8140 -> 8131
, "ῼ" => "ῳ" // 8188 -> 8179
, "Ⅰ" => "ⅰ" // 8544 -> 8560
, "Ⅱ" => "ⅱ" // 8545 -> 8561
, "Ⅲ" => "ⅲ" // 8546 -> 8562
, "Ⅳ" => "ⅳ" // 8547 -> 8563
, "Ⅴ" => "ⅴ" // 8548 -> 8564
, "Ⅵ" => "ⅵ" // 8549 -> 8565
, "Ⅶ" => "ⅶ" // 8550 -> 8566
, "Ⅷ" => "ⅷ" // 8551 -> 8567
, "Ⅸ" => "ⅸ" // 8552 -> 8568
, "Ⅹ" => "ⅹ" // 8553 -> 8569
, "Ⅺ" => "ⅺ" // 8554 -> 8570
, "Ⅻ" => "ⅻ" // 8555 -> 8571
, "Ⅼ" => "ⅼ" // 8556 -> 8572
, "Ⅽ" => "ⅽ" // 8557 -> 8573
, "Ⅾ" => "ⅾ" // 8558 -> 8574
, "Ⅿ" => "ⅿ" // 8559 -> 8575
, "Ⓐ" => "ⓐ" // 9398 -> 9424
, "Ⓑ" => "ⓑ" // 9399 -> 9425
, "Ⓒ" => "ⓒ" // 9400 -> 9426
, "Ⓓ" => "ⓓ" // 9401 -> 9427
, "Ⓔ" => "ⓔ" // 9402 -> 9428
, "Ⓕ" => "ⓕ" // 9403 -> 9429
, "Ⓖ" => "ⓖ" // 9404 -> 9430
, "Ⓗ" => "ⓗ" // 9405 -> 9431
, "Ⓘ" => "ⓘ" // 9406 -> 9432
, "Ⓙ" => "ⓙ" // 9407 -> 9433
, "Ⓚ" => "ⓚ" // 9408 -> 9434
, "Ⓛ" => "ⓛ" // 9409 -> 9435
, "Ⓜ" => "ⓜ" // 9410 -> 9436
, "Ⓝ" => "ⓝ" // 9411 -> 9437
, "Ⓞ" => "ⓞ" // 9412 -> 9438
, "Ⓟ" => "ⓟ" // 9413 -> 9439
, "Ⓠ" => "ⓠ" // 9414 -> 9440
, "Ⓡ" => "ⓡ" // 9415 -> 9441
, "Ⓢ" => "ⓢ" // 9416 -> 9442
, "Ⓣ" => "ⓣ" // 9417 -> 9443
, "Ⓤ" => "ⓤ" // 9418 -> 9444
, "Ⓥ" => "ⓥ" // 9419 -> 9445
, "Ⓦ" => "ⓦ" // 9420 -> 9446
, "Ⓧ" => "ⓧ" // 9421 -> 9447
, "Ⓨ" => "ⓨ" // 9422 -> 9448
, "Ⓩ" => "ⓩ" // 9423 -> 9449
, "𐐦" => "𐑎" // 66598 -> 66638
, "𐐧" => "𐑏" // 66599 -> 66639
);

$utf8_string = mb_strtolower($utf8_string, "UTF-8");

$utf8_string = strtr ($utf8_string, $additional_replacements);

Return $utf8_string ;
) //strtolower_utf8_extended()

Case change functions

strtolower

Converts characters in a string to lower case.

Syntax:

string strtolower(string str);

Converts a string to lowercase. Returns the result of the translation.

It should be noted that if the locale is incorrectly configured, the function will produce, to put it mildly, strange results when working with Cyrillic letters.

$str = "HeLLo World";

$str = strtolower($str);

// prints hello world

strtoupper

Converts the specified string to uppercase.

Syntax:

string strtoupper(string str);

Converts the string to upper case. Returns the result of the conversion. This function works well with English letters, but can be weird with Russian ones.

$str = "Hello World";

$str = strtoupper($str);

// will print HELLO WORLD

Converts the first character of a string to uppercase.

Syntax:

string ucfirst(string str);

Returns a string whose first character is uppercase.

$str = "hello world";

$str = ucfirst($str);

// prints Hello world

Converts the first character of each word in a string to uppercase.

Syntax:

string ucwords(string str);

Returns a string in which the first character of each word in the string is capitalized.

A word here refers to a section of a line preceded by a white space character: space, new line, page feed, carriage return, horizontal and vertical tab.

Cyrillic characters may not be converted correctly.

$str = "hello world";

$str = ucfirst($str);

// prints Hello World