These are functions that manipulate strings in various ways. There are also dedicated chapters on regular expressions and URL processing.
For information about the operation mechanism of strings, especially information about single quotes, double quotes, and escape sequences, see the string entry.
Comprehensive collection of string functions:
addcslashes — Use backslashes to escape characters in strings in C language style
addslashes — Use backslashes to quote strings
bin2hex — Convert binary data to hexadecimal Represents
chop — Alias for rtrim
chr — Returns the specified character
chunk_split — Splits the string into small pieces
convert_cyr_string — Converts characters from one Cyrillic character to another
convert_uudecode — Decodes a uuencode Encoded string
convert_uuencode — Use uuencode to encode a string
count_chars — Return information about the characters used in the string
crc32 — Calculate the crc32 polynomial of a string
crypt — One-way string hashing
echo — Output one or more strings
explode — Use one string to split another string
fprintf — Write the formatted string to the stream
get_html_translation_table — Return the translation table after using htmlspecialchars and htmlentities
hebrev — Convert logical-Hebrew to visual-Hebrew
hebrevc — Convert logical-Hebrew to visual-Hebrew text (visual-Hebrew), and convert newlines
hex2bin — Convert hexadecimal strings to binary strings
html_entity_decode — Convert all HTML entities to their applicable characters
htmlentities — Convert all applicable characters to HTML entities
htmlspecialchars_decode — Convert special characters to HTML entities
htmlspecialchars — Convert special characters to HTML entities
implode — Convert the values of a one-dimensional array into a string
join — Alias implode
lcfirst — Make a character The first character of the string is lowercase
levenshtein — Calculate the edit distance between two strings
localeconv — Get numeric formatting information
ltrim — Remove the blank characters (or other characters) at the beginning of the string
md5_file — Calculate MD5 hash value of a specified file
md5 — Calculate the MD5 hash value 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 — Insert HTML newline mark before all new lines in the string
number_format — Format a number with thousand separators
ord — Return the ASCII code value of the character
parse_str — Parse the string into multiple Variable
print — Output string
printf — Output formatted string
quoted_printable_decode — Convert a quoted-printable string to an 8 bit string
quoted_printable_encode — Convert a 8 bit string to a quoted-printable string
quotemeta — Quote meta characters
rtrim — Remove blank characters (or other characters) at the end of the string
setlocale — Set locale information
sha1_file — Calculate the sha1 hash value of the file
sha1 — Calculate the sha1 hash value of the string
similar_text — Calculate the similarity of two strings
soundex — Calculate the soundex key of a string
sprintf — Return a formatted string
sscanf — Parse the input characters according to the specified format
str_getcsv — Parse CSV string For an array
str_ireplace — Case-ignoring version of str_replace
str_pad — Fill a string with another string to the specified length
str_repeat — Repeat a string
str_replace — Substring replacement
str_rot13 — For characters String execution ROT13 conversion
str_shuffle — Randomly shuffle a string
str_split — Convert a string into an array
str_word_count — Return the usage of words in a string
strcasecmp — Binary safe comparison of strings (case-insensitive )
strchr — alias strstr
strcmp — Binary safe string comparison
strcoll — Locale-based string comparison
strcspn — Get the length of the starting substring of a non-matching mask
strip_tags — From characters Remove HTML and PHP tags from a string
stripcslashes — Dequote a string escaped using addcslashes
stripos — Find the first occurrence of a string (case-insensitive)
stripslashes — Dequote a quoted string
stristr — A case-ignoring version of the strstr function
strlen — Get the length of a string
strnatcasecmp — Compare strings using the “natural ordering” algorithm (case-insensitive)
strnatcmp — Compare strings using the natural ordering algorithm
strncasecmp — Binary-safe comparison of several characters at the beginning of the string (case-insensitive)
strncmp — Binary safe comparison of several characters at the beginning of a string
strpbrk — Find any character in a set of characters in a string
strpos — Find the first occurrence of a string
strrchr — Find the specified character in a string The last occurrence of
strrev — Reverse a string
strripos — Calculate the position of the last occurrence of the specified string in the target string (case-insensitive)
strrpos — Calculate the position of the specified string in the target string The position of the last occurrence
strspn — Calculate the length of the first substring in the string where all characters exist in the specified character set.
strstr — Find the first occurrence of a string
strtok — Mark split string
strtolower — Convert the string to lowercase
strtoupper — Convert the string to uppercase
strtr — Convert the specified character
substr_compare — Binary Safely compare strings (compare specified lengths from offset positions)
substr_count — Count the number of occurrences of a string
substr_replace — Replace a substring of a string
substr — Return a substring of a string
trim — Remove a string Blank characters (or other characters) at the beginning and end
ucfirst — Convert the first letter of the string to uppercase
ucwords — Convert the first letter of each word in the string to uppercase
vfprintf — Write the formatted string Incoming stream
vprintf — Output formatted string
vsprintf — Return formatted string
wordwrap — Break the string into a specified number of words