02-05-2008
variables usage without dereferencing
Hi All,
I came across a bit of code that seems to work, even though I didn't expect it to (now that's wierd!)
#!/bin/sh
set -x
nn=15
if [ nn -eq 15 ]
then
echo "is true"
fi
The above code ends up comparing the string "nn" to number 15, but still evaluates to true. Here's the output when i run it :
+ nn=15
+ [
nn -eq 15 ]
+ echo is true
is true
while with [ "$nn" -eq 15 ], I get:
+ nn=15
+ [
15 -eq 15 ]
+ echo is true
is true
which is what I expect.
By the way, if you assign nn=25 and run test nn -eq 15, it evaluates to false.
Any Ideas how the integer comparison is working without dereferencing the variable?
Last edited by ag79; 02-06-2008 at 11:36 AM..
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IS_INT(3) 1 IS_INT(3)
is_int - Find whether the type of a variable is integer
SYNOPSIS
bool is_int (mixed $var)
DESCRIPTION
Finds whether the type of the given variable is integer.
Note
To test if a variable is a number or a numeric string (such as form input, which is always a string), you must use is_numeric(3).
PARAMETERS
o $var
- The variable being evaluated.
RETURN VALUES
Returns TRUE if $var is an integer, FALSE otherwise.
EXAMPLES
Example #1
is_int(3) example
<?php
$values = array(23, "23", 23.5, "23.5", null, true, false);
foreach ($values as $value) {
echo "is_int(";
var_export($value);
echo ") = ";
var_dump(is_int($value));
}
?>
The above example will output:
is_int(23) = bool(true)
is_int('23') = bool(false)
is_int(23.5) = bool(false)
is_int('23.5') = bool(false)
is_int(NULL) = bool(false)
is_int(true) = bool(false)
is_int(false) = bool(false)
SEE ALSO
is_bool(3), is_float(3), is_numeric(3), is_string(3), is_array(3), is_object(3).
PHP Documentation Group IS_INT(3)