PHP's Common string method

1.trim: Remove whitespace characters (or other characters) from the end of a string
eg

$text = "            There is a few words.       ";
Print_r (Trim ($text));
2.ltrim: Remove the left white space character.

3.rtrim: Remove the white space character to the right.

4.str_pad (): fills the string as required. The first argument is the string to fill, the second is the padding length, the third parameter is the fill symbol,
The fourth parameter is the direction of the fill (

Str_pad_left: String left fill.

Str_pad_right : String right fill.

Str_pad_both: String ends fill

）

eg

$input = "Alice.";

Echo Str_pad ($input, 10, "-="); alice.-=-=

Echo Str_pad ($input, "* *", str_pad_both);  alice.*****

5.strtolower (): string str all lowercase strings.

6.strtoupper (): This function converts the string str to all uppercase strings.

7.ucfirst (): The first character of the string is changed to uppercase.

8.ucwords (): string The first letter of each word is capitalized.

9.NL2BR (): Converts the string "\ n" to the HTML line break "<br/>"; the second parameter indicates whether to use XHTML-compatible line breaks

eg
Echo nl2br ("Welcome\r\nthis is my HTML document", false);//welcome
                                                          This is my HTML document

10.htmlspecialchars (): Turn the specified special symbols into entities, such as <>, etc.
eg

Echo htmlspecialchars ("<a href= ' # ' >Test</a>");//<a href= ' # ' >Test</a>

11.strip_tags (): Removes HTML and PHP tags from the string.

eg
$text 1 = "<p>test paragraph.</p><!--Comment--><a href= ' # ' >other text</a>";
echo $text 1;//test paragraph.

               Other text

12.strrev (): Reverses the string backwards. Reverses the string.

$text 2 = "Hello World";
Echo Strrev ($text 2);//dlrow Olleh

13.strlen (): Gets the string length.

14.number_format (): Format a number in thousands separators

eg
$number = 1234.56;
echo  Number_format ($number);//1,235

echo  Number_format ($number, 2);//1,234.56

echo  Number_format ($number, 2, ",", "");//1234,56

15.MD5 (): cryptographic function

16.STRCMP (): Binary secure string comparison

eg
$var 1 = "Hello";
$var 2 = "Hello";
if (strcmp ($var 1, $var 2)!== 0) {
    echo "$var 1 is not equal to $var 2 in a case sensitive string Comarison";
}

17.STRNCMP (): Binary security compares several characters at the beginning of a string, similar to strcmp, except that you can specify the length that is used when two string comparisons are made.

eg

$arr 1 = $arr 2 = Array ("Img12.png", "Img10.png", "Img2.png", "img1.png");

Usort ($arr 1, "strcmp");//array ([0] = img1.png [1] = = Img10.png [2] = = Img12.png [3] = = img2.png)

18.STRCASECMP (): Binary Security comparison string (case insensitive)

19.STRNATCMP (): Comparing strings using natural sorting algorithms

eg
$arr 1 = $arr 2 = Array ("Img12.png", "Img10.png", "Img2.png", "img1.png");

Usort ($arr 2, "strnatcmp");//array ([0] = img1.png [1] = = Img2.png [2] = = Img10.png [3] = = img12.png)

20.similar_text (): Calculates the similarity of two strings

PHP's Common string method