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PHP string functions are an integral part of PHP core. No installation is required to use these functions.
| Function | Description |
|---|---|
| addcslashes() | Returns adding a backslash before the specified character bar string. |
| addslashes() | Returns a string with backslashes added before predefined characters. |
| bin2hex() | Convert a string of ASCII characters to a hexadecimal value. |
| chop() | Remove blank characters or other characters on the right side of the string. |
| chr() | Returns the character from the specified ASCII value. |
| chunk_split() | Split the string into a series of smaller parts. |
| convert_cyr_string() | Convert a string from one Cyrillic character set to another. |
| convert_uudecode() | Decode the uuencode encoded string. |
| convert_uuencode() | Encode a string using the uuencode algorithm. |
| count_chars() | Returns information about the characters used in a string. |
| crc32() | Calculate the 32-bit CRC of a string. |
| crypt() | One-way string encryption (hashing). |
| echo() | Output one or more strings. |
| explode() | Break up the string into an array. |
| fprintf() | Write the formatted string to the specified output stream. |
| get_html_translation_table() | Returns the translation table used by htmlspecialchars() and htmlentities(). |
| hebrev() | Convert Hebrew text to visible text. |
| hebrevc() | Convert Hebrew text to visible text and convert new lines (\n) to 0c6dc11e160d3b678d68754cc175188a. |
| hex2bin() | Convert a string of hexadecimal values to ASCII characters. |
| html_entity_decode() | Convert HTML entities to characters. |
| htmlentities() | Convert characters to HTML entities. |
| htmlspecialchars_decode() | Convert some predefined HTML entities into characters. |
| htmlspecialchars() | Convert some predefined characters into HTML entities. |
| implode() | Returns a string composed of array elements. |
| join() | An alias for implode(). |
| lcfirst() | Convert the first character of the string to lowercase. |
| levenshtein() | Returns the Levenshtein distance between two strings. |
| localeconv() | Returns local number and currency format information. |
| ltrim() | Remove whitespace characters or other characters on the left side of the string. |
| md5() | Computes the MD5 hash of a string. |
| md5_file() | Calculate the MD5 hash of the file. |
| metaphone() | Calculate the metaphone key of a string. |
| money_format() | Returns a string formatted as a currency string. |
| nl_langinfo() | Returns specific local information. |
| nl2br() | Insert an HTML newline character before each new line in the string. |
| number_format() | Format a number in thousands groups. |
| ord() | Returns the ASCII value of the first character in the string. |
| parse_str() | Parse the query string into variables. |
| print() | Output one or more strings. |
| printf() | Output formatted string. |
| quoted_printable_decode() | Convert quoted-printable string to 8-bit string. |
| quoted_printable_encode() | Convert 8-bit string to quoted-printable string. |
| quotemeta() | Quote metacharacters. |
| rtrim() | Remove whitespace characters or other characters on the right side of the string. |
| setlocale() | Set regional information (regional information). |
| sha1() | Computes the SHA-1 hash of a string. |
| sha1_file() | Compute the SHA-1 hash of a file. |
| similar_text() | Calculate the similarity of two strings. |
| soundex() | Calculate the soundex key of a string. |
| sprintf() | Write the formatted string into the variable. |
| sscanf() | Parses input from a string according to the specified format. |
| str_getcsv() | Parse the CSV string into an array. |
| str_ireplace() | Replace some characters in a string (not case sensitive). |
| str_pad() | Padding the string to the new length. |
| str_repeat() | Repeat the string the specified number of times. |
| str_replace() | Replace some characters in the string (case sensitive). |
| str_rot13() | Perform ROT13 encoding on a string. |
| str_shuffle() | Randomly shuffles all characters in the string. |
| str_split() | Split the string into an array. |
| str_word_count() | Count the number of words in a string. |
| strcasecmp() | Compares two strings (not case sensitive). |
| strchr() | Find the first occurrence of a string in another string. (Alias for strstr().) |
| strcmp() | Compares two strings (case sensitive). |
| strcoll() | Compares two strings (according to local settings). |
| strcspn() | Returns the number of characters to search in a string before finding any part of some specified characters. |
| strip_tags() | Strip HTML and PHP tags from strings. |
| stripcslashes() | Remove backslashes added by the addcslashes() function. |
| stripslashes() | Remove backslashes added by addslashes() function. |
| stripos() | Returns the position of the first occurrence of a string in another string (not case sensitive). |
| stristr() | Find the first occurrence of a string in another string (case insensitive). |
| strlen() | Returns the length of the string. |
| strnatcasecmp() | Uses a "natural ordering" algorithm to compare two strings (not case sensitive). |
| strnatcmp() | Uses a "natural ordering" algorithm to compare two strings (case sensitive). |
| strncasecmp() | String comparison of the first n characters (not case sensitive). |
| strncmp() | String comparison of the first n characters (case sensitive). |
| strpbrk() | Find any character in a set of characters in a string. |
| strpos() | Returns the position of the first occurrence of a string in another string (case sensitive). |
| strrchr() | Find the last occurrence of a string in another string. |
| strrev() | Reverse a string. |
| strripos() | Find the last occurrence of a string in another string (not case sensitive). |
| strrpos() | Find the last occurrence of a string in another string (case sensitive). |
| strspn() | Returns the number of specific characters contained in a string. |
| strstr() | Find the first occurrence of a string in another string (case sensitive). |
| strtok() | Split the string into smaller strings. |
| strtolower() | Convert the string to lowercase letters. |
| strtoupper() | Convert the string to uppercase letters. |
| strtr() | Convert specific characters in the string. |
| substr() | Returns a part of the string. |
| substr_compare() | Compares two strings starting at the specified starting position (binary safe and selective case sensitive). |
| substr_count() | Count the number of times a substring appears in a string. |
| substr_replace() | Replace part of a string with another string. |
| trim() | Remove whitespace characters and other characters on both sides of the string. |
| ucfirst() | Convert the first character in the string to uppercase. |
| ucwords() | Convert the first character of each word in the string to uppercase. |
| vfprintf() | Write the formatted string to the specified output stream. |
| vprintf() | Output formatted string. |
| vsprintf() | Write the formatted string into the variable. |
| wordwrap() | Break the string into a specified number of words |
Example during form validation Use function:
function test_input($data) {
$data = trim($data); //移除字符串两侧的空白字符和其他字符。
$data = stripslashes($data); //删除由 addslashes() 函数添加的反斜杠。
$data = htmlspecialchars($data); //把一些预定义的字符转换为 HTML 实体。
return $data;
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