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Top Forums Shell Programming and Scripting Check if a variable has a value assigned? Post 302312859 by cfajohnson on Sunday 3rd of May 2009 11:48:32 PM
Old 05-04-2009

Code:
if [ -z "${var+X}" ]
then
  echo var is unset
elif [ -z "$var" ]
then
  echo var is set but empty
else
  echo "The value of \$var is $var"
fi

 

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IS_SCALAR(3)								 1							      IS_SCALAR(3)

is_scalar - Finds whether a variable is a scalar

SYNOPSIS
bool is_scalar (mixed $var) DESCRIPTION
Finds whether the given variable is a scalar. Scalar variables are those containing an integer, float, string or boolean. Types array, object and resource are not scalar. Note is_scalar(3) does not consider resource type values to be scalar as resources are abstract datatypes which are currently based on integers. This implementation detail should not be relied upon, as it may change. Note is_scalar(3) does not consider NULL to be scalar. PARAMETERS
o $var - The variable being evaluated. RETURN VALUES
Returns TRUE if $var is a scalar, FALSE otherwise. EXAMPLES
Example #1 is_scalar(3) example <?php function show_var($var) { if (is_scalar($var)) { echo $var; } else { var_dump($var); } } $pi = 3.1416; $proteins = array("hemoglobin", "cytochrome c oxidase", "ferredoxin"); show_var($pi); show_var($proteins) ?> The above example will output: 3.1416 array(3) { [0]=> string(10) "hemoglobin" [1]=> string(20) "cytochrome c oxidase" [2]=> string(10) "ferredoxin" } SEE ALSO
is_float(3), is_int(3), is_numeric(3), is_real(3), is_string(3), is_bool(3), is_object(3), is_array(3). PHP Documentation Group IS_SCALAR(3)
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