A string is a sequence of characters, like “Hello world!”.
PHP String Functions
We will look at some commonly used functions to manipulate strings.
Get The Length of a String
The PHP strlen() function returns the length of a string.
The example below returns the length of the string “Hello Robert Karamagi!”:
Example
<!DOCTYPE html>
<html>
<body>
<?php
echo strlen(“Hello Robert Karamagi!”);
?>
</body>
</html>
Output
Count The Number of Words in a String
The PHP str_word_count() function counts the number of words in a string:
Example
<!DOCTYPE html>
<html>
<body>
<?php
echo str_word_count(“Hello Robert Karamagi!”);
?>
</body>
</html>
Output
Reverse a String
The PHP strrev() function reverses a string:
Example
<!DOCTYPE html>
<html>
<body>
<?php
echo strrev(“Hello Robert Karamagi!”);
?>
</body>
</html>
Output
Search For a Specific Text Within a String
The PHP strpos() function searches for a specific text within a string.
If a match is found, the function returns the character position of the first match. If no match is found, it will return FALSE.
The example below searches for the text “Karamagi” in the string “Hello Robert Karamagi!”:
Example
<!DOCTYPE html>
<html>
<body>
<?php
echo strpos(“Hello Robert Karamagi!”, “Karamagi”);
?>
</body>
</html>
Output
Tip: The first character position in a string is 0 (not 1).
Replace Text Within a String
The PHP str_replace() function replaces some characters with some other characters in a string.
The example below replaces the text “Robert” with “Prof.”:
Example
<!DOCTYPE html>
<html>
<body>
<?php
echo str_replace(“Robert”, “Prof.”, “Hello Robert Karamagi!”);
?>
</body>
</html>
Output
PHP 5 String Functions
The PHP string functions are part of the PHP core. No installation is required to use these functions.
Function |
Description |
|---|---|
| addcslashes() | Returns a string with backslashes in front of the specified characters |
| addslashes() | Returns a string with backslashes in front of predefined characters |
| bin2hex() | Converts a string of ASCII characters to hexadecimal values |
| chop() | Removes whitespace or other characters from the right end of a string |
| chr() | Returns a character from a specified ASCII value |
| chunk_split() | Splits a string into a series of smaller parts |
| convert_cyr_string() | Converts a string from one Cyrillic character-set to another |
| convert_uudecode() | Decodes a uuencoded string |
| convert_uuencode() | Encodes a string using the uuencode algorithm |
| count_chars() | Returns information about characters used in a string |
| crc32() | Calculates a 32-bit CRC for a string |
| crypt() | One-way string hashing |
| echo() | Outputs one or more strings |
| explode() | Breaks a string into an array |
| fprintf() | Writes a formatted string to a specified output stream |
| get_html_translation_table() | Returns the translation table used by htmlspecialchars() and htmlentities() |
| hebrev() | Converts Hebrew text to visual text |
| hebrevc() | Converts Hebrew text to visual text and new lines (\n) into <br> |
| hex2bin() | Converts a string of hexadecimal values to ASCII characters |
| html_entity_decode() | Converts HTML entities to characters |
| htmlentities() | Converts characters to HTML entities |
| htmlspecialchars_decode() | Converts some predefined HTML entities to characters |
| htmlspecialchars() | Converts some predefined characters to HTML entities |
| implode() | Returns a string from the elements of an array |
| join() | Alias of implode() |
| lcfirst() | Converts the first character of a string to lowercase |
| levenshtein() | Returns the Levenshtein distance between two strings |
| localeconv() | Returns locale numeric and monetary formatting information |
| ltrim() | Removes whitespace or other characters from the left side of a string |
| md5() | Calculates the MD5 hash of a string |
| md5_file() | Calculates the MD5 hash of a file |
| metaphone() | Calculates the metaphone key of a string |
| money_format() | Returns a string formatted as a currency string |
| nl_langinfo() | Returns specific local information |
| nl2br() | Inserts HTML line breaks in front of each newline in a string |
| number_format() | Formats a number with grouped thousands |
| ord() | Returns the ASCII value of the first character of a string |
| parse_str() | Parses a query string into variables |
| print() | Outputs one or more strings |
| printf() | Outputs a formatted string |
| quoted_printable_decode() | Converts a quoted-printable string to an 8-bit string |
| quoted_printable_encode() | Converts an 8-bit string to a quoted printable string |
| quotemeta() | Quotes meta characters |
| rtrim() | Removes whitespace or other characters from the right side of a string |
| setlocale() | Sets locale information |
| sha1() | Calculates the SHA-1 hash of a string |
| sha1_file() | Calculates the SHA-1 hash of a file |
| similar_text() | Calculates the similarity between two strings |
| soundex() | Calculates the soundex key of a string |
| sprintf() | Writes a formatted string to a variable |
| sscanf() | Parses input from a string according to a format |
| str_getcsv() | Parses a CSV string into an array |
| str_ireplace() | Replaces some characters in a string (case-insensitive) |
| str_pad() | Pads a string to a new length |
| str_repeat() | Repeats a string a specified number of times |
| str_replace() | Replaces some characters in a string (case-sensitive) |
| str_rot13() | Performs the ROT13 encoding on a string |
| str_shuffle() | Randomly shuffles all characters in a string |
| str_split() | Splits a string into an array |
| str_word_count() | Count the number of words in a string |
| strcasecmp() | Compares two strings (case-insensitive) |
| strchr() | Finds the first occurrence of a string inside another string (alias of strstr()) |
| strcmp() | Compares two strings (case-sensitive) |
| strcoll() | Compares two strings (locale based string comparison) |
| strcspn() | Returns the number of characters found in a string before any part of some specified characters are found |
| strip_tags() | Strips HTML and PHP tags from a string |
| stripcslashes() | Unquotes a string quoted with addcslashes() |
| stripslashes() | Unquotes a string quoted with addslashes() |
| stripos() | Returns the position of the first occurrence of a string inside another string (case-insensitive) |
| stristr() | Finds the first occurrence of a string inside another string (case-insensitive) |
| strlen() | Returns the length of a string |
| strnatcasecmp() | Compares two strings using a “natural order” algorithm (case-insensitive) |
| strnatcmp() | Compares two strings using a “natural order” algorithm (case-sensitive) |
| strncasecmp() | String comparison of the first n characters (case-insensitive) |
| strncmp() | String comparison of the first n characters (case-sensitive) |
| strpbrk() | Searches a string for any of a set of characters |
| strpos() | Returns the position of the first occurrence of a string inside another string (case-sensitive) |
| strrchr() | Finds the last occurrence of a string inside another string |
| strrev() | Reverses a string |
| strripos() | Finds the position of the last occurrence of a string inside another string (case-insensitive) |
| strrpos() | Finds the position of the last occurrence of a string inside another string (case-sensitive) |
| strspn() | Returns the number of characters found in a string that contains only characters from a specified charlist |
| strstr() | Finds the first occurrence of a string inside another string (case-sensitive) |
| strtok() | Splits a string into smaller strings |
| strtolower() | Converts a string to lowercase letters |
| strtoupper() | Converts a string to uppercase letters |
| strtr() | Translates certain characters in a string |
| substr() | Returns a part of a string |
| substr_compare() | Compares two strings from a specified start position (binary safe and optionally case-sensitive) |
| substr_count() | Counts the number of times a substring occurs in a string |
| substr_replace() | Replaces a part of a string with another string |
| trim() | Removes whitespace or other characters from both sides of a string |
| ucfirst() | Converts the first character of a string to uppercase |
| ucwords() | Converts the first character of each word in a string to uppercase |
| vfprintf() | Writes a formatted string to a specified output stream |
| vprintf() | Outputs a formatted string |
| vsprintf() | Writes a formatted string to a variable |
| wordwrap() | Wraps a string to a given number of characters |
Robert Karamagi 