PHP:
substr("abcdef", start, length);
Golang:
string[start:start+length]
Example:
PHP:
substr("abcdef", 2, 3);
Golang:
func Substr(str string, start int, length int) (string){
return str[start:start+length]}
fmt.Print("abcdef"[2:5])
PHP substr
PHP original manual for substr
[
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php.net
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substr
(PHP 4, PHP 5, PHP 7) substr — Return part of a string
Description
string substr
( string $string
, int $start
[, int $length
] )
Parameters
-
string
-
The input string. Must be one character or longer.
-
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
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"
?>
-
length
-
If length is given and is positive, the string
returned will contain at most length characters
beginning from start (depending 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 truncation 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.
Examples
Example #3 Basic substr() 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() 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;
?>
Output of the above example in PHP 7:
1) 'pe'
2) '54'
3) 'gr'
4) '1'
5) ''
6) ''
7) '1200'
Output of the above example in PHP 5:
1) 'pe'
2) '54'
3) 'gr'
4) '1'
5) false
6) false
7) '1200'
Errors/Exceptions
Returns FALSE on error.
<?php
var_dump(substr('a', 2)); // bool(false)
?>
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