PHP Common functions

Mathematical functions

1.abs (): Absolute value
$abs = ABS (-4.2); 4.2 Numeric Absolute number

2.ceil (): Into a method to take the whole
echo ceil (9.999); 10 floating point number in one rounding

3.floor (): Rounding off the Rounding method
echo Floor (9.999); 9 floating-point numbers directly out of the decimal part

4.fmod (): floating-point number

  $x = 5.7;
  $y = 1.3;//two floating-point numbers, x>y floating-point remainder
  $r = Fmod ($x, $y);
 //$r equals 0.5, because 4 * 1.3 + 0.5 = 5.7

5.pow (): Returns the number of n-th square
 echo pow (-1, 20);//1 base number |n quadratic square value

6.round (): Floating-point rounding
 echo round (1.95583, 2);//1.96, a value | Preserves the number of digits after the decimal point, the default is 0 rounded result

7.sqrt (): square root
& Nbsp;echo sqrt (9); 3 square root of the radical

8.max (): Maximum value
Echo max (1, 3, 5, 6, 7);//7
Multiple numbers or arrays returns the maximum value
Echo max (Array (2, 4, 5));//5
9.min (): Minimum value
Input: Multiple numbers or arrays
output: Returns the minimum value

10.mt_rand (): Better random number
Input: Min | max, output: Random number value in Random return range
Echo Mt_rand (0,9);//n

11.rand (): Random number input: Min | max, output: Random number returns the value in the range

12.pi (): Get pi Value
To go to a space or other character:

13.trim (): Remove spaces or other predefined characters at each end of a string
$str = "\r\nhello world!\r\n";
echo Trim ($STR);
Input: Target string return value: Cleared string

14.rtrim (): Remove whitespace or other predefined characters to the right of the string
$str = "Hello world!\n\n";
echo RTrim ($STR);

15.chop (): Alias for RTrim ()

16.ltrim (): Remove space or other predefined characters to the left of the string
$str = "\r\nhello world!";
Echo LTrim ($STR);

17.dirname (): Returns the directory portion of the path
Echo dirname ("c:/testweb/home.php"); C:/testweb
Input: A string containing the path return value: Returns the directory portion of the file path

String generation and conversion:

18.str_pad (): Fills a string with the specified length
$STR = "Hello World";
Echo Str_pad ($str, 20, ".");
Input: string to fill | The length of the new string | The string to use for padding, which is blank by default
Output: String after completion

19.str_repeat (): repeating the specified string
Echo str_repeat (".", 13); String to repeat | The number of times a string will be repeated 13 points

20.str_split (): Splitting a string into an array
Print_r (Str_split ("Hello"));
Input: String to be split | The length of each array element, default 1
Output: Array of strings after splitting

21.strrev (): Invert string
Echo Strrev ("Hello world!"); !dlrow Olleh
Output: String after reverse order of target string

22.wordwrap (): String wrapping with a specified length
$STR = "An example in a long word is:
Supercalifragulistic ";
Echo WordWrap ($STR, 15);
Input: Target string | maximum width
Output: New string after wrapping

23.str_shuffle (): Randomly disrupts all characters in a string
Echo str_shuffle ("Hello World");
Input: Target string sequential output: scrambled string

24.PARSE_STR (): Parsing a string into a variable
Parse_str ("Id=23&name=john%20adams", $myArray);
Print_r ($myArray);
Input: String to parse | The array name of the stored variable
Output: return array ([id] = [name] = John Adams)

25.number_format (): Formatting numeric input by thousands grouping: number to format | Specifies how many decimals | Specifies a string to use as a decimal point | Specifies a string to use as a thousands separator
Output: 1,000,000 1,000,000.00 1.000.000,00

Case Conversion:

26.strtolower (): string converted to lowercase
Echo strtolower ("Hello world!");
Target String Lowercase string

27.strtoupper (): string converted to uppercase
Echo strtoupper ("Hello world!");
Output: Uppercase string

28.ucfirst (): Capitalize the first letter of the string
echo ucfirst ("Hello World"); Hello World

29.ucwords (): string each word first character to uppercase
echo ucwords ("Hello World"); Hello World
HTML Tag associations:

30.htmlentities (): Convert character to HTML entity
$str = "John & ' Adams '";
Echo htmlentities ($str, Ent_compat); John & ' Adams '

31.htmlspecialchars (): Predefined word representable HTML encoding

32.NL2BR (): \ n escaped as <br> label
Echo nl2br ("One line.\nanother line.");
Output: Processed string

33.strip_tags (): Stripping HTML, XML, and PHP tags
Echo strip_tags ("Hello <b>world!</b>");

　
34.addcslashes (): Adds a backslash to an escaped character in a string before the specified character
$str = "Hello, my name is John Adams.";
Echo $str;
Echo addcslashes ($str, ' m ');
Input: Target string | Specify a specific character or range of characters

35.stripcslashes (): Remove backslash added by addcslashes ()
Echo stripcslashes ("Hello, \my Na\me is Kai ji\m.");
Destination string Hello, my name is Kai Jim.

36.addslashes (): Add a backslash before specifying a predefined character
$str = "Who ' s John Adams?";
echo addslashes ($STR);
Output: "\" and null in the target string are escaped

37.stripslashes (): Remove the escape character added by Addslashes ()
Echo stripslashes ("who\ ' s John Adams?"); Clear escape sign who's John Adams?

38.quotemeta (): Add a backslash before some of the predefined characters in the string
$STR = "Hello World". (Can you hear me?) ";
echo Quotemeta ($STR);
Hello world\. \ (Can you hear me\?\)

39.CHR (): Returns the character from the specified ASCII value
Echo Chr (052); ASCII value returns the corresponding character

40.ord (): Returns the ASCII value of the first character of a string
echo ord ("Hello"); The ASCII value of the first character of a string
string comparison:

41.STRCASECMP (): Case-insensitive comparison of two strings
echo strcasecmp ("Hello world!", "Hello world!");
Input: Two target string output: Big 1| etc 0| Small-1

42.STRCMP (): Case-sensitive comparison of two strings

43.STRNCMP (): Compares the first n characters of a string, case sensitive
Call: int strncmp (String $str 1, String $str 2, int $len)

44.STRNCASECMP (): Compares the first n characters of a string, not case-sensitive
Call: int strncasecmp (String $str 1, String $str 2, int $len)

45.STRNATCMP (): Natural order Method compares string length, case-sensitive
Call: int strnatcmp (String $str 1, String $str 2)
Input: Target string

46.STRNATCASECMP (): Natural order Method compares string length, case-insensitive
Call: int strnatcasecmp (String $str 1, String $str 2)
String cutting and splicing:

47.chunk_split (): Dividing a string into small chunks
Call: Str chunk_split (str $body [, int $len [, str $end]]
Input: $body target string, $len length, $str insertion terminator output: Split string

48.strtok (): Cut string
Call: Str strtok (str $str, str $token)
Target string $str, $token for flag cut returns the cut string

49.explode (): Use one string to split another string for a flag
Call: Array explode (str $sep, str $str [, int $limit])
Input: $sep as a delimiter, $str the target string, $limit returns the array with a maximum number of elements output: The array formed after the string is split

50.implode (): joins, concatenate array values into strings with subscription characters
Call: String implode (String $glue, array $pieces)
$glue default, connect directly with "

51.SUBSTR (): Intercept string
Call: String substr (string $string, int $start [, int $length])

String Lookup substitution：
52.str_replace (): String substitution operation, case-sensitive
Call Mix Str_replace (Mix $search, Mix $replace, Mix $subject [, int & $num])
Input: $search Find the string, $replace the replacement string, $subject looked up string, & $num output: Returns the result of the substitution

53.str_ireplace () string substitution operation, case insensitive
Call: Mix Str_ireplace (Mix $search, Mix $replace, Mix $subject [, int & $count])
Input: $search find string, $replace replacement string, $subject,& $num output: Returns the replaced result

54.substr_count (): Counts the number of occurrences of a string in another string
Call: int Substr_count (String $haystack, string $needle [, int $offset = 0 [, int $length]])

55.substr_replace (): Replaces a string in another string
Call: Mixed Substr_replace (mixed $string, string $replacement, int $start [, int $length])

56.similar_text (): Returns the number of identical characters in two strings
Call: int Similar_text (str $str 1,str $str 2)
Input: Two strings for comparison
Output: Shaping, number of identical characters

57.STRRCHR (): Returns a string in another string where the last occurrence of the position begins at the end of the string
Call: String STRRCHR (String $haystack, mixed $needle)

58.STRSTR (): Returns a string in another string starting at the end of the string
Call: String Strstr (String $str, String $needle, bool $before _needle)

59.STRCHR (): An alias of Strstr () that returns the first occurrence of a string in another string, starting at the end of the string
Call: String Strstr (String $haystack, mixed $needle [, bool $before _needle = false])

60.STRISTR (): Returns a string in another string starting at the end of the string, case-insensitive

Call: String Stristr (String $haystack, mixed $needle [, bool $before _needle = false])

61.STRTR (): Converts some characters in a string

Call: String Strtr (String $str, String $from, String $to)

62.strpos (): Find where a character in a string first appears
Call: int Strpos (String $haystack, mixed $needle [, int $offset = 0])

63.stripos (): Looks for the first occurrence of a character in a string, case-insensitive invocation: int Stripos (String $haystack, string $needle [, int $offset])

64.strrpos (): Find the last occurrence of a character in a string
Call: int Strrpos (String $haystack, string $needle [, int $offset = 0])

65.strripos (): Finds the last occurrence of a character in a string, is not case sensitive
Call: int Strripos (String $haystack, string $needle [, int $offset])

66.STRSPN (): Returns the first mask-compliant substring length in a string called: int strspn (String $str 1, String $str 2 [, int $start [, int $length]])

67.STRCSPN (): Returns the length of a string in a string that does not match mask
Call: int strcspn (String $str 1, String $str 2 [, int $start [, int $length]])
Input: $str 1 is queried, $str 2 query string, $start the character to start querying, $length is the query length output: Returns from the beginning to the first few characters
String statistics:

68.str_word_count (): Statistics string contains the number of words
Call: Mix str_word_count (str $str, [])
Input: Target string output: Number of statistics offices

69.strlen (): Statistical string length int strlen (str $str)
Input: Target string output: integer length

70.count_chars (): Count all occurrences of letters in the string (0..255) Call: Mixed Count_chars (string $string [, int $mode])
String encoding:

71.md5 (): String MD5 encoding
$str = "Hello";
echo MD5 ($STR);

PHP Common functions