05-06-2011
Difference between [condition] and [[condition]] and ((condition)) when used with if condition
Executed the following if conditions .. and got different results .
only (( )) gave correct o/p with all scenarios .
Can anybody please let me know what is the difference between [condition] and [[condition]] and ((condition)) when used with if condition.
And why each condition gave different result.
1.
if [ 234 > 71 ];then
echo "correct"
else
echo "wrong"
fi
O/p : correct
2.
$if [[ 234 > 71 ]];then
echo "correct"
else
echo "wrong"
fi
o/p : wrong
3.
if [[ 234 > 700 ]];then
echo "correct"
else
echo "wrong"
fi
o/p : wrong
4.
if [ 234 > 700 ];then
echo "correct"
else
echo "wrong"
fi
o/p : correct
5.
$if (( 234 > 700 ));then
echo "correct"
else
echo "wrong"
fi
o/p : wrong
6.
if (( 234 > 71 ));then
echo "correct"
else
echo "wrong"
fi
o/p : correct
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ROUND(3) 1 ROUND(3)
round - Rounds a float
SYNOPSIS
float round (float $val, [int $precision], [int $mode = PHP_ROUND_HALF_UP])
DESCRIPTION
Returns the rounded value of $val to specified $precision (number of digits after the decimal point). $precision can also be negative or
zero (default).
Note
PHP doesn't handle strings like "12,300.2" correctly by default. See converting from strings.
PARAMETERS
o $val
- The value to round
o $precision
- The optional number of decimal digits to round to.
o $mode
- Use one of the following constants to specify the mode in which rounding occurs.
+--------------------+---------------------------------------------------+
| Constant | |
| | |
| | Description |
| | |
+--------------------+---------------------------------------------------+
| | |
| PHP_ROUND_HALF_UP | |
| | |
| | Round $val up to $precision decimal places away |
| | from zero, when it is half way there. Making 1.5 |
| | into 2 and -1.5 into -2. |
| | |
| | |
|PHP_ROUND_HALF_DOWN | |
| | |
| | Round $val down to $precision decimal places |
| | towards zero, when it is half way there. Making |
| | 1.5 into 1 and -1.5 into -1. |
| | |
| | |
|PHP_ROUND_HALF_EVEN | |
| | |
| | Round $val to $precision decimal places towards |
| | the next even value. |
| | |
| | |
|PHP_ROUND_HALF_ODD | |
| | |
| | Round $val to $precision decimal places towards |
| | the next odd value. |
| | |
+--------------------+---------------------------------------------------+
RETURN VALUES
The rounded value
EXAMPLES
Example #1
round(3) examples
<?php
echo round(3.4); // 3
echo round(3.5); // 4
echo round(3.6); // 4
echo round(3.6, 0); // 4
echo round(1.95583, 2); // 1.96
echo round(1241757, -3); // 1242000
echo round(5.045, 2); // 5.05
echo round(5.055, 2); // 5.06
?>
Example #2
$mode examples
<?php
echo round(9.5, 0, PHP_ROUND_HALF_UP); // 10
echo round(9.5, 0, PHP_ROUND_HALF_DOWN); // 9
echo round(9.5, 0, PHP_ROUND_HALF_EVEN); // 10
echo round(9.5, 0, PHP_ROUND_HALF_ODD); // 9
echo round(8.5, 0, PHP_ROUND_HALF_UP); // 9
echo round(8.5, 0, PHP_ROUND_HALF_DOWN); // 8
echo round(8.5, 0, PHP_ROUND_HALF_EVEN); // 8
echo round(8.5, 0, PHP_ROUND_HALF_ODD); // 9
?>
Example #3
$mode with precision examples
<?php
/* Using PHP_ROUND_HALF_UP with 1 decimal digit precision */
echo round( 1.55, 1, PHP_ROUND_HALF_UP); // 1.6
echo round( 1.54, 1, PHP_ROUND_HALF_UP); // 1.5
echo round(-1.55, 1, PHP_ROUND_HALF_UP); // -1.6
echo round(-1.54, 1, PHP_ROUND_HALF_UP); // -1.5
/* Using PHP_ROUND_HALF_DOWN with 1 decimal digit precision */
echo round( 1.55, 1, PHP_ROUND_HALF_DOWN); // 1.5
echo round( 1.54, 1, PHP_ROUND_HALF_DOWN); // 1.5
echo round(-1.55, 1, PHP_ROUND_HALF_DOWN); // -1.5
echo round(-1.54, 1, PHP_ROUND_HALF_DOWN); // -1.5
/* Using PHP_ROUND_HALF_EVEN with 1 decimal digit precision */
echo round( 1.55, 1, PHP_ROUND_HALF_EVEN); // 1.6
echo round( 1.54, 1, PHP_ROUND_HALF_EVEN); // 1.5
echo round(-1.55, 1, PHP_ROUND_HALF_EVEN); // -1.6
echo round(-1.54, 1, PHP_ROUND_HALF_EVEN); // -1.5
/* Using PHP_ROUND_HALF_ODD with 1 decimal digit precision */
echo round( 1.55, 1, PHP_ROUND_HALF_ODD); // 1.5
echo round( 1.54, 1, PHP_ROUND_HALF_ODD); // 1.5
echo round(-1.55, 1, PHP_ROUND_HALF_ODD); // -1.5
echo round(-1.54, 1, PHP_ROUND_HALF_ODD); // -1.5
?>
CHANGELOG
+--------+---------------------------------------------------+
|Version | |
| | |
| | Description |
| | |
+--------+---------------------------------------------------+
| 5.3.0 | |
| | |
| | The $mode parameter was introduced. |
| | |
| 5.2.7 | |
| | |
| | The inner workings of round(3) was changed to |
| | conform to the C99 standard. |
| | |
+--------+---------------------------------------------------+
SEE ALSO
ceil(3), floor(3), number_format(3).
PHP Documentation Group ROUND(3)