substr_replace(3) [php man page]
SUBSTR_REPLACE(3) 1 SUBSTR_REPLACE(3) substr_replace - Replace text within a portion of a string SYNOPSIS
mixed substr_replace (mixed $string, mixed $replacement, mixed $start, [mixed $length]) DESCRIPTION
substr_replace(3) replaces a copy of $string delimited by the $start and (optionally) $length parameters with the string given in $replace- ment. PARAMETERS
o $string - The input string. An array of strings can be provided, in which case the replacements will occur on each string in turn. In this case, the $replacement, $start and $length parameters may be provided either as scalar values to be applied to each input string in turn, or as arrays, in which case the corresponding array element will be used for each input string. o $replacement - The replacement string. o $start - If $start is positive, the replacing will begin at the $start'th offset into $string. If $start is negative, the replacing will begin at the $start'th character from the end of $string. o $length - If given and is positive, it represents the length of the portion of $string which is to be replaced. If it is negative, it rep- resents the number of characters from the end of $string at which to stop replacing. If it is not given, then it will default to strlen( $string ); i.e. end the replacing at the end of $string. Of course, if $length is zero then this function will have the effect of inserting $replacement into $string at the given $start offset. RETURN VALUES
The result string is returned. If $string is an array then array is returned. EXAMPLES
Example #1 Simple substr_replace(3) examples <?php $var = 'ABCDEFGH:/MNRPQR/'; echo "Original: $var<hr /> "; /* These two examples replace all of $var with 'bob'. */ echo substr_replace($var, 'bob', 0) . "<br /> "; echo substr_replace($var, 'bob', 0, strlen($var)) . "<br /> "; /* Insert 'bob' right at the beginning of $var. */ echo substr_replace($var, 'bob', 0, 0) . "<br /> "; /* These next two replace 'MNRPQR' in $var with 'bob'. */ echo substr_replace($var, 'bob', 10, -1) . "<br /> "; echo substr_replace($var, 'bob', -7, -1) . "<br /> "; /* Delete 'MNRPQR' from $var. */ echo substr_replace($var, '', 10, -1) . "<br /> "; ?> Example #2 Using substr_replace(3) to replace multiple strings at once <?php $input = array('A: XXX', 'B: XXX', 'C: XXX'); // A simple case: replace XXX in each string with YYY. echo implode('; ', substr_replace($input, 'YYY', 3, 3))." "; // A more complicated case where each replacement is different. $replace = array('AAA', 'BBB', 'CCC'); echo implode('; ', substr_replace($input, $replace, 3, 3))." "; // Replace a different number of characters each time. $length = array(1, 2, 3); echo implode('; ', substr_replace($input, $replace, 3, $length))." "; ?> The above example will output: A: YYY; B: YYY; C: YYY A: AAA; B: BBB; C: CCC A: AAAXX; B: BBBX; C: CCC NOTES
Note This function is binary-safe. SEE ALSO
str_replace(3), substr(3), String access and modification by character. PHP Documentation Group SUBSTR_REPLACE(3)
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SUBSTR(3) 1 SUBSTR(3) substr - Return part of a string SYNOPSIS
string substr (string $string, int $start, [int $length]) DESCRIPTION
Returns the portion of $string specified by the $start and $length parameters. PARAMETERS
o $string - The input string. Must be one character or longer. o $start - If $start is non-negative, the returned string will start at the $start'th position in $string, counting from zero. For instance, in the string ' abcdef', the character at position 0 is ' a', the character at position 2 is ' c', and so forth. If $start is negative, the returned string will start at the $start'th character from the end of $string. If $string is less than or equal to $start characters long, FALSE will be returned. Example #1 Using a negative $start <?php $rest = substr("abcdef", -1); // returns "f" $rest = substr("abcdef", -2); // returns "ef" $rest = substr("abcdef", -3, 1); // returns "d" ?> o $length - If $length is given and is positive, the string returned will contain at most $length characters beginning from $start (depend- ing on the length of $string). If $length is given and is negative, then that many characters will be omitted from the end of $string (after the start position has been calculated when a $start is negative). If $start denotes the position of this trunca- tion or beyond, false will be returned. If $length is given and is 0, FALSE or NULL, an empty string will be returned. If $length is omitted, the substring starting from $start until the end of the string will be returned. Example #2 Using a negative $length <?php $rest = substr("abcdef", 0, -1); // returns "abcde" $rest = substr("abcdef", 2, -1); // returns "cde" $rest = substr("abcdef", 4, -4); // returns false $rest = substr("abcdef", -3, -1); // returns "de" ?> RETURN VALUES
Returns the extracted part of $string; or FALSE on failure, or an empty string. CHANGELOG
+--------------+---------------------------------------------------+ | Version | | | | | | | Description | | | | +--------------+---------------------------------------------------+ |5.2.2 - 5.2.6 | | | | | | | If the $start parameter indicates the position | | | of a negative truncation or beyond, false is | | | returned. Other versions get the string from | | | start. | | | | +--------------+---------------------------------------------------+ EXAMPLES
Example #3 Basic substr(3) usage <?php echo substr('abcdef', 1); // bcdef echo substr('abcdef', 1, 3); // bcd echo substr('abcdef', 0, 4); // abcd echo substr('abcdef', 0, 8); // abcdef echo substr('abcdef', -1, 1); // f // Accessing single characters in a string // can also be achieved using "square brackets" $string = 'abcdef'; echo $string[0]; // a echo $string[3]; // d echo $string[strlen($string)-1]; // f ?> Example #4 substr(3) casting behaviour <?php class apple { public function __toString() { return "green"; } } echo "1) ".var_export(substr("pear", 0, 2), true).PHP_EOL; echo "2) ".var_export(substr(54321, 0, 2), true).PHP_EOL; echo "3) ".var_export(substr(new apple(), 0, 2), true).PHP_EOL; echo "4) ".var_export(substr(true, 0, 1), true).PHP_EOL; echo "5) ".var_export(substr(false, 0, 1), true).PHP_EOL; echo "6) ".var_export(substr("", 0, 1), true).PHP_EOL; echo "7) ".var_export(substr(1.2e3, 0, 4), true).PHP_EOL; ?> The above example will output: 1) 'pe' 2) '54' 3) 'gr' 4) '1' 5) false 6) false 7) '1200' ERRORS
/EXCEPTIONS Returns FALSE on error. Example #5 <?php var_dump(substr('a', 1)); // bool(false) ?> SEE ALSO
strrchr(3), substr_replace(3), preg_match(3), trim(3), mb_substr(3), wordwrap(3), String access and modification by character. PHP Documentation Group SUBSTR(3)