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Top Forums Shell Programming and Scripting Sed: would like to return an error for empty string Post 303045785 by bedtime on Monday 13th of April 2020 09:00:26 AM
Old 04-13-2020
Sed: would like to return an error for empty string

There are actually two things that I want to do:

1. Detect if there is a 3 digit number and if so return an error (working)
2. Detect if there is an empty string and return an error if so (not working)

I would like to do 1 & 2 using the sed command only once; I'm trying to do things correctly and efficiently.

I have so far:
Code:
echo "" | sed -n -r '/[0-9]{3}/{q100}; //{q100}'; echo $?

(For newbies: -n quiets text output, -r allows for GNU program to do true regex, {q100} returns error '100', '$?' is the last returned result)



The result is 0, which is not what I want as the string is empty. My attempt is the portion '//{q100}', but I can see that it is difficult to test against nothing-quite perplexing actually.
 

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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)
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