# String Functions

## Introduction

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.

## Requirements

No external libraries are needed to build this extension.

## Installation

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_SALT_LENGTH` integer
`CRYPT_STD_DES` integer
`CRYPT_EXT_DES` integer
`CRYPT_MD5` integer
`CRYPT_BLOWFISH` integer
`HTML_SPECIALCHARS` (integer)
`HTML_ENTITIES` (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_getcsv — Parse a CSV string into an array
- 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 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