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Top Forums UNIX for Dummies Questions & Answers Testing for non-zero length string Post 302580088 by methyl on Wednesday 7th of December 2011 12:12:04 PM
Old 12-07-2011
It's a string test. Put double quotes round the string wherever you mention it. Without the quotes it is a syntax error in most Shells.
Code:
echo "$nothing"
if [ -z "${nothing}" ]; then echo "nothing is a zero length string"; fi
if [ -n "${nothing}" ]; then echo "nothing is also a non-zero length string, apparently"; fi

 

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SUBSTR_COMPARE(3)							 1							 SUBSTR_COMPARE(3)

substr_compare - Binary safe comparison of two strings from an offset, up to length characters

SYNOPSIS
int substr_compare (string $main_str, string $str, int $offset, [int $length], [bool $case_insensitivity = false]) DESCRIPTION
substr_compare(3) compares $main_str from position $offset with $str up to $length characters. PARAMETERS
o $main_str - The main string being compared. o $str - The secondary string being compared. o $offset - The start position for the comparison. If negative, it starts counting from the end of the string. o $length - The length of the comparison. The default value is the largest of the length of the $str compared to the length of $main_str less the $offset. o $case_insensitivity - If $case_insensitivity is TRUE, comparison is case insensitive. RETURN VALUES
Returns < 0 if $main_str from position $offset is less than $str, > 0 if it is greater than $str, and 0 if they are equal. If $offset is equal to or greater than the length of $main_str, or the $length is set and is less than 1 (prior to PHP 5.6), substr_compare(3) prints a warning and returns FALSE. CHANGELOG
+--------+---------------------------------------------------+ |Version | | | | | | | Description | | | | +--------+---------------------------------------------------+ | 5.6.0 | | | | | | | $length may now be 0. | | | | | 5.1.0 | | | | | | | Added the possibility to use a negative $offset. | | | | +--------+---------------------------------------------------+ EXAMPLES
Example #1 A substr_compare(3) example <?php echo substr_compare("abcde", "bc", 1, 2); // 0 echo substr_compare("abcde", "de", -2, 2); // 0 echo substr_compare("abcde", "bcg", 1, 2); // 0 echo substr_compare("abcde", "BC", 1, 2, true); // 0 echo substr_compare("abcde", "bc", 1, 3); // 1 echo substr_compare("abcde", "cd", 1, 2); // -1 echo substr_compare("abcde", "abc", 5, 1); // warning ?> SEE ALSO
strncmp(3). PHP Documentation Group SUBSTR_COMPARE(3)
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