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Last updated: Tue, 19 Sep 2006

CLIII. String Functions


These functions all manipulate strings in various ways. Some more specialized sections can be found in the regular expression and URL handling sections.

For information on how strings behave, especially with regard to usage of single quotes, double quotes, and escape sequences, see the Strings entry in the Types section of the manual.


No external libraries are needed to build this extension.


There is no installation needed to use these functions; they are part of the PHP core.

Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.




CRYPT_MD5 integer




ENT_COMPAT (integer)

ENT_QUOTES (integer)

ENT_NOQUOTES (integer)

CHAR_MAX (integer)

LC_CTYPE (integer)

LC_NUMERIC (integer)

LC_TIME (integer)

LC_COLLATE (integer)

LC_MONETARY (integer)

LC_ALL (integer)

LC_MESSAGES (integer)

STR_PAD_LEFT (integer)

STR_PAD_RIGHT (integer)

STR_PAD_BOTH (integer)

See Also

For even more powerful string handling and manipulating functions take a look at the POSIX regular expression functions and the Perl compatible regular expression functions.

Table of Contents
addcslashes -- Quote string with slashes in a C style
addslashes -- Quote string with slashes
bin2hex --  Convert binary data into hexadecimal representation
chop -- Alias of rtrim()
chr -- Return a specific character
chunk_split -- Split a string into smaller chunks
convert_cyr_string --  Convert from one Cyrillic character set to another
convert_uudecode --  Decode a uuencoded string
convert_uuencode --  Uuencode a string
count_chars --  Return information about characters used in a string
crc32 -- Calculates the crc32 polynomial of a string
crypt -- One-way string encryption (hashing)
echo -- Output one or more strings
explode -- Split a string by string
fprintf -- Write a formatted string to a stream
get_html_translation_table --  Returns the translation table used by htmlspecialchars() and htmlentities()
hebrev --  Convert logical Hebrew text to visual text
hebrevc --  Convert logical Hebrew text to visual text with newline conversion
html_entity_decode --  Convert all HTML entities to their applicable characters
htmlentities --  Convert all applicable characters to HTML entities
htmlspecialchars_decode --  Convert special HTML entities back to characters
htmlspecialchars --  Convert special characters to HTML entities
implode -- Join array elements with a string
join -- Alias of implode()
levenshtein --  Calculate Levenshtein distance between two strings
localeconv -- Get numeric formatting information
ltrim --  Strip whitespace (or other characters) from the beginning of a string
md5_file -- Calculates the md5 hash of a given file
md5 -- Calculate the md5 hash of a string
metaphone -- Calculate the metaphone key of a string
money_format -- Formats a number as a currency string
nl_langinfo --  Query language and locale information
nl2br --  Inserts HTML line breaks before all newlines in a string
number_format -- Format a number with grouped thousands
ord -- Return ASCII value of character
parse_str -- Parses the string into variables
print -- Output a string
printf -- Output a formatted string
quoted_printable_decode --  Convert a quoted-printable string to an 8 bit string
quotemeta -- Quote meta characters
rtrim --  Strip whitespace (or other characters) from the end of a string
setlocale -- Set locale information
sha1_file -- Calculate the sha1 hash of a file
sha1 -- Calculate the sha1 hash of a string
similar_text --  Calculate the similarity between two strings
soundex -- Calculate the soundex key of a string
sprintf -- Return a formatted string
sscanf --  Parses input from a string according to a format
str_ireplace --  Case-insensitive version of str_replace().
str_pad --  Pad a string to a certain length with another string
str_repeat -- Repeat a string
str_replace --  Replace all occurrences of the search string with the replacement string
str_rot13 -- Perform the rot13 transform on a string
str_shuffle -- Randomly shuffles a string
str_split --  Convert a string to an array
str_word_count --  Return information about words used in a string
strcasecmp --  Binary safe case-insensitive string comparison
strchr -- Alias of strstr()
strcmp -- Binary safe string comparison
strcoll -- Locale based string comparison
strcspn --  Find length of initial segment not matching mask
strip_tags -- Strip HTML and PHP tags from a string
stripcslashes --  Un-quote string quoted with addcslashes()
stripos --  Find position of first occurrence of a case-insensitive string
stripslashes --  Un-quote string quoted with addslashes()
stristr --  Case-insensitive strstr()
strlen -- Get string length
strnatcasecmp --  Case insensitive string comparisons using a "natural order" algorithm
strnatcmp --  String comparisons using a "natural order" algorithm
strncasecmp --  Binary safe case-insensitive string comparison of the first n characters
strncmp --  Binary safe string comparison of the first n characters
strpbrk --  Search a string for any of a set of characters
strpos --  Find position of first occurrence of a string
strrchr --  Find the last occurrence of a character in a string
strrev -- Reverse a string
strripos --  Find position of last occurrence of a case-insensitive string in a string
strrpos --  Find position of last occurrence of a char in a string
strspn --  Find length of initial segment matching mask
strstr -- Find first occurrence of a string
strtok -- Tokenize string
strtolower -- Make a string lowercase
strtoupper -- Make a string uppercase
strtr -- Translate certain characters
substr_compare --  Binary safe optionally case insensitive comparison of 2 strings from an offset, up to length characters
substr_count -- Count the number of substring occurrences
substr_replace -- Replace text within a portion of a string
substr -- Return part of a string
trim -- Strip whitespace (or other characters) from the beginning and end of a string
ucfirst -- Make a string's first character uppercase
ucwords --  Uppercase the first character of each word in a string
vfprintf -- Write a formatted string to a stream
vprintf -- Output a formatted string
vsprintf -- Return a formatted string
wordwrap --  Wraps a string to a given number of characters using a string break character

Last updated: Tue, 19 Sep 2006