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.

String functions

AddSlashes

Name

AddSlashes — quote string with slashes

Description

string addslashes(string str);

Chop

Chr

Returns a string with backslashes before characters that need to be quoted in database queries etc. These characters are single quote ('), double quote ("), backslash (\) and NUL (the null byte).

Name

Chop — remove trailing whitespace

Description

string chop(string str);

Returns the argument string without trailing whitespace.

Example 1. chop() example

$trimmed = Chop($line);

Name

Chr — return a specific character

Description

string chr(int ascii);

Returns a one-character string containing the character specified by ascii.

Example 1. chr() example

$str .= chr(27); /* add an escape character at the end of $str */

/* Often this is more useful */

$str = sprintf("The string ends in escape: %c", 27);

This function complements ord. See also sprintf with a format string of %c.

convert_cyr_string

Name

convert_cyr_string — Convert from one Cyrillic character set to another

Description

string convert_cyr_string(string str, string from, string to);

This function converts the given string from one Cyrillic character set to another. The from and to arguments are single characters that represent the source and target Cyrillic character sets. The supported types are:

k - koi8-r
w - windows-1251
i - iso8859-5
a - x-cp866
d - x-cp866
m - x-mac-cyrillic

crypt

echo

Name

crypt — DES-encrypt a string

Description

string crypt(string str, string [salt]);

crypt will encrypt a string using the standard Unix DES encryption method. Arguments are a string to be encrypted and an optional two-character salt string to base the encryption on. See the Unix man page for your crypt function for more information.

If the salt argument is not provided, it will be randomly generated by PHP.

Some operating systems support more than one type of encryption. In fact, sometimes the standard DES encryption is replaced by an MD5 based encryption algorithm. The encryption type is triggered by the salt argument. At install time, PHP determines the capabilities of the crypt function and will accept salts for other encryption types. If no salt is provided, PHP will auto-generate a standard 2-character DES salt by default unless the default encryption type on the system is MD5 in which case a random MD5- compatible salt is generated.

There is no decrypt function, since crypt uses a one-way algorithm.

Name

echo — output one or more strings

Description

echo(string arg1, string [argn]...);

Outputs all parameters.

explode

Name

explode — split a string by string

Description

flush

array explode(string separator, string string);

Returns an array of strings containing the elements separated by separator.

Example 1. explode() example

$pizza = "piece1 piece2 piece3 piece4 piece5 piece6";

$pieces = explode(" ", $pizza);

Description

void flush(void);

Flushes the output buffers of PHP and whatever backend PHP is using (CGI, a web server, etc.) This effectively tries to push all the output so far to the user's browser.

htmlspecialchars

Name

htmlspecialchars — Convert special characters to HTML entities.

Description

string htmlspecialchars(string string);

Certain characters have special significance in HTML, and should be represented by HTML entities if they are to preserve their meanings. This function returns a string with these conversions made.

At present, the translations that are done are:

'&' (ampersand) becomes '&'
'"' (double quote) becomes '"'
'<' (less than) becomes '<'
'>' (greater than) becomes '>'

Note that this functions does not translate anything beyond what is listed above. For full entity translation, see htmlentities.

htmlentities

Name

htmlentities — Convert all applicable characters to HTML entities.

Description

string htmlentities(string string);

This function is identical to htmlspecialchars in all ways, except that all characters which have HTML entity equivalents are translated into these entities.

At present, the ISO-8859-1 character set is used. See also htmlspecialchars and nl2br.

implode

Name

implode — join array elements with a string

Description

string implode(array pieces, string glue);

Returns a string containing a string representation of all the array elements in the same order, with the glue string between each element.

join

ltrim

Example 1. implode() example

$colon_separated = implode($array, ":");

Description

string join(array pieces, string glue); join is an alias to implode, and is identical in every way.

Name

ltrim — Strip whitespace from the beginning of a string.

Description

string ltrim(string str);

This function strips whitespace from the start of a string and returns the stripped string. See also chop and trim.

md5

nl2br

Ord

Name

md5 — calculate the md5 hash of a string

Description

string md5(string str);

Calculates the MD5 hash of str using the RSA Data Security, Inc. MD5 Message-Digest Algorithm.

Name

nl2br — Converts newlines to HTML line breaks.

Description

string nl2br(string string);

Returns string with '<BR>' inserted before all newlines. See also htmlspecialchars and htmlentities.

Name

Ord — return ASCII value of character

Description

int ord(string string);

Returns the ASCII value of the first character of string. This function complements chr.

Example 1. ord() example

if (ord($str) == 10) {

echo("The first character of \$str is a line feed.\n");

}

parse_str

Name

parse_str — parses the string into variables

Description

void parse_str(string str);

Parses str as if it were the query string passed via an URL and sets variables in the current scope.

Example 1. Using parse_str

$str = "first=value&second[]=this+works&second[]=another"; parse_str($str);

echo $first; /* prints "value" */

echo $second[0]; /* prints "this works" */ echo $second[1]; /* prints "another" */

print

printf

Name

print — output a string

Description

print(string arg);

Outputs arg.

Name

printf — output a formatted string

Description

int printf(string format, mixed [args]...);

Produces output according to format, which is described in the documentation for sprintf. See also: print, sprintf, and flush.

quoted_printable_decode

Name

quoted_printable_decode — Convert a quoted-printable string to an 8 bit string

Description

string quoted_printable_decode(string str);

This function returns an 8-bit binary string corresponding to the decoded quoted printable string. This function is similar to imap_qprint, except this one does not require the IMAP module to work.

QuoteMeta

Name

QuoteMeta — quote meta characters

Description

int quotemeta(string str);

Returns a version of str with a backslash character (\) before every character that is among these:

. \\ + * ? [ ^ ] ( $ )

See also addslashes, htmlentities, htmlspecialchars, and nl2br.

rawurldecode

Name

rawurldecode — decode URL-encoded strings

Description

string rawurldecode(string str);

Returns a string in which the sequences with percent (%) signs followed by two hex digits have been replaced with literal characters. For example, the string

foo%20bar%40baz

decodes into

foo bar@baz

rawurlencode

Name

rawurlencode — URL-encode according to RFC1738

Description

string rawurlencode(string str);

Returns a string in which all non-alphanumeric characters except

-_.

have been replaced with a percent (%) sign followed by two hex digits. This is the encoding described in RFC1738 for protecting literal characters from being interpreted as special URL delimiters, and for protecting URL's from being mangled by transmission media with character conversions (like some email systems). For example, if you want to include a password in an ftp url:

Example 1. rawurlencode() example 1

echo '<A HREF="ftp://user:', rawurlencode ('foo @+%/'), '@ftp.my.com/x.txt">';

Or, if you pass information in a path info component of the url:

Example 2. rawurlencode() example 2

echo '<A HREF="http://x.com/department_list_script/',

rawurlencode ('sales and marketing/Miami'), '">';

setlocale

Name

setlocale — set locale information

Description

string setlocale(string category, string locale);

category is a string specifying the category of the functions affected by the locale setting:

LC_ALL for all of the below
LC_COLLATE for string comparison - not currently implemented in PHP
LC_CTYPE for character classification and conversion, for example

strtoupper
LC_MONETARY for localeconv() - not currently implemented in PHP
LC_NUMERIC for decimal separator
LC_TIME for date and time formatting with strftime

If locale is the empty string "", the locale names will be set from the values of environment variables with the same names as the above categories, or from "LANG".

If locale is zero or "0", the locale setting is not affected, only the current setting is returned.

Setlocale returns the new current locale, or false if the locale functionality is not implemented in the plattform, the specified locale does not exist or the category name is invalid. An invalid category name also causes a warning message.

soundex

Name

soundex — calculate the soundex key of a string

Description

string soundex(string str);

Calculates the soundex key of str.

Soundex keys have the property that words pronounced similarly produce the same soundex key, and can thus be used to simplify searches in databases where you know the pronunciation but not the spelling. This soundex function returns a string 4 characters long, starting with a letter.

This particular soundex function is one described by Donald Knuth in "The Art Of Computer Programming, vol. 3: Sorting And Searching", Addison-Wesley (1973), pp. 391-392.

Example 1. Soundex Examples

soundex("Euler") == soundex("Ellery") == 'E460'; soundex("Gauss") == soundex("Ghosh") == 'G200'; soundex("Knuth") == soundex("Kant") == 'H416'; soundex("Lloyd") == soundex("Ladd") == 'L300'; soundex("Lukasiewicz") == soundex("Lissajous") == 'L222';

sprintf

Name

sprintf — return a formatted string

Description

sprintf(string format, mixed [args]...);

Returns a string produced according to the formatting string format.

The format string is composed by zero or more directives: ordinary characters (excluding %) that are copied directly to the result, and conversion specifications, each of which results in fetching its own parameter. This applies to both sprintf and printf

Each conversion specification consists of these elements, in order:

An optional padding specifier that says what character will be used for padding the results to the right string size. This may be a space character or a 0 (zero character). The default is to pad with spaces. An alternate padding character can be specified by prefixing it with a single quote ('). See the examples below.
An optional alignment specifier that says if the result should be left-justified or right-justified. The default is right-justified; a - character here will make it left-justified.
An optional number, a width specifier that says how many characters (minimum) this conversion should result in.
An optional precision specifier that says how many decimal digits should be displayed for floating-point numbers. This option has no effect for other types than double.
A type specifier that says what type the argument data should be

treated as. Possible types:

a literal percent character. No argument is required.

the argument is treated as an integer, and presented as a binary number.

the argument is treated as an integer, and presented as the character with that ASCII value. the argument is treated as an integer, and presented as a decimal number.

the argument is treated as a double, and presented as a floating-point number. the argument is treated as an integer, and presented as an octal number.

the argument is treated as and presented as a string.

the argument is treated as an integer and presented as a hexadecimal number (with lowercase letters).

the argument is treated as an integer and presented as a hexadecimal number (with uppercase letters).

Examples

Example 1. sprintf: zero-padded integers

$isodate = sprintf("%04d-%02d-%02d", $year, $month, $day);

strchr

Name

strchr — Find the first occurrence of a character.

Description

string strchr(string haystack, string needle);

This function is an alias for strstr, and is identical in every way.

strcmp

Name

strcmp — binary safe string comparison

Description

int strcmp(string str1, string str2);

Returns < 0 if str1 is less than str2; > 0 if str1 is greater than str2, and 0 if they are equal. Note that this comparison is case sensitive.

strcspn

Name

strcspn — find length of initial segment not matching mask

Description

int strcspn(string str1, string str2);

Returns the length of the initial segment of str1 which does not contain any of the characters in str2. See also strspn.

StripSlashes

Name

StripSlashes — un-quote string quoted with addslashes

Description

strlen

string stripslashes(string str);

Returns a string with backslashes stripped off. (\' becomes ' and so on.) Double backslashes are made into a single backslash.

Name

strlen — get string length

Description

int strlen(string str);

Returns the length of string.

strrpos

Name

strrpos — Find position of last occurrence of a char in a string.

Description

string strrpos(string haystack, char needle);

Returns the numeric position of the last occurrence of needle in the haystack string. Note that the needle in this case can only be a single character. If a string is passed as the needle, then only the first character of that string will be used.

If needle is not found, returns false.

If needle is not a string, it is converted to an integer and applied as the ordinal value of a character. See also strpos, strrchr, substr, and strstr.

strpos

Name

strpos — Find position of first occurrence of a string.

Description

string strpos(string haystack, string needle, int [offset]);

Returns the numeric position of the first occurrence of needle in the haystack string. Unlike the

strrpos, this function can take a full string as the needle parameter and the entire string will be used. If needle is not found, returns false.

If needle is not a string, it is converted to an integer and applied as the ordinal value of a character.

The optional offset parameter allows you to specify which character in haystack to start searching. The position returned is still relative to the the beginning of haystack.

See also strrpos, strrchr, substr, and strstr.

strrchr

Name

strrchr — Find the last occurrence of a character in a string.

Description

string strrchr(string haystack, string needle);

This function returns the portion of haystack which starts at the last occurrence of needle and goes until the end of haystack.

Returns false if needle is not found.

If needle is not found, false is returned.

If needle contains more than one character, the first is used.

If needle is not a string, it is converted to an integer and applied as the ordinal value of a character.

Example 1. strrchr() example

// get last directory in $PATH

$dir = substr( strrchr( $PATH, ":" ), 1 );

// get everything after last newline

$text = "Line 1\nLine 2\nLine 3";

$last = substr( strrchr( $text, 10 ), 1 );

strrev

Name

strrev — Reverse a string.

Description

string strrev(string string);

Returns string, reversed.

strcspn

Name

strcspn — find length of initial segment matching mask

Description

strstr

strtok

int strspn(string str1, string str2);

Returns the length of the initial segment of str1 which consists entirely of characters in str2. See also strcspn.

Name

strstr — Find first occurrence of a string.

Description

string strstr(string haystack, string needle);

Returns all of haystack from the first occurrence of needle to the end. If needle is not found, returns false.

If needle is not a string, it is converted to an integer and applied as the ordinal value of a character. See also strrchr, substr, and ereg.

Name

strtok — tokenize string

Description

string strtok(string arg1, string arg2);

strtok() is used to tokenize a string. That is, if you have a string like "This is an example string" you could tokenize this string into its individual words by using the space character as the token.

Example 1. strtok() example

$string = "This is an example string";

$tok = strtok($string," "); while($tok) {

echo "Word=$tok<br>";

$tok = strtok(" ");

}

Note that only the first call to strtok uses the string argument. Every subsequent call to strtok only needs the token to use, as it keeps track of where it is in the current string. To start over, or to tokenize a new string you simply call strtok with the string argument again to initialize it. Note that you may put multiple tokens in the token parameter. The string will be tokenized when any one of the characters in the argument are found.

strtolower

Name

strtolower — Make a string lowercase.

Description

string strtolower(string str);

Returns string with all alphabetic characters converted to lowercase.

Note that 'alphabetic' is determined by the current locale. This means that in i.e. the default "C" locale, characters such as umlaut-A (Ä) will not be converted.

strtoupper

Name

strtoupper — Make a string uppercase.

Description

string strtoupper(string string);

Returns string with all alphabetic characters converted to uppercase.

Note that 'alphabetic' is determined by the current locale. For instance, in the default "C" locale characters such as umlaut-a (ä) will not be converted.

strtr

Name

strtr — Translate certain characters.

Description

string strtr(string str, string from, string to);

This function operates on str, translating all occurrences of each character in from to the corresponding character in to and returning the result.

If from and to are different lengths, the extra characters in the longer of the two are ignored.

Example 1. strtr() example

$addr = strtr($addr, "äåö", "aao");

substr

Name

substr — Return part of a string.

Description

string substr(string string, int start, int [length]);

Substr returns the portion of string specified by the start and length parameters.

If start is positive, the returned string will start at the start'th character of string. Examples:

$rest = substr("abcdef", 1); // returns "bcdef"

$rest = substr("abcdef", 1, 3); // returns "bcd"

If start is negative, the returned string will start at the start'th character from the end of string. Examples:

$rest = substr("abcdef", -1); // returns "f"

$rest = substr("abcdef", -2); // returns "ef"

$rest = substr("abcdef", -3, 1); // returns "d"

If length is given and is positive, the string returned will end length characters from start. If this would result in a string with negative length, then the returned string will contain the single character at start.

If length is given and is negative, the string returned will end length characters from the end of string. If this would result in a string with negative length, then the returned string will contain the single character at start. Examples:

trim

$rest = substr("abcdef", -1, -1); // returns "bcde"

Name

trim — Strip whitespace from the beginning and end of a string.

Description

string trim(string str);

This function strips whitespace from the start and the end of a string and returns the stripped string. See also chop and ltrim.

ucfirst

Name

ucfirst — Make a string's first character uppercase

Description

string ucfirst(string str);

Capitalizes the first character of str if that character is alphabetic.

Note that 'alphabetic' is determined by the current locale. For instance, in the default "C" locale characters such as umlaut-a (ä) will not be converted.

ucwords

Name

ucwords — Uppercase the first character of each word in a string

Description

string ucwords(string str);

Capitalizes the first character of each word in str if that character is alphabetic. See also strtoupper, strtolower and ucfirst.