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Find whether the type of a variable is integer
(PHP 4, PHP 5)
Example 2592. is_int() example<?phpThe above example will output: is integerRelated Examples ( Source code ) » is_int Examples ( Source code ) » Returns true if $a is an integer Examples ( Source code ) » Addendum Examples ( Source code ) » A stack with type restricted to int Examples ( Source code ) » Search the Web using Google API Examples ( Source code ) » Feed Validator Code Examples / Notes » is_intlogan
[[Editors note: Or you can simply use is_numeric()]] Some people have offered their ways to find out if a string from a form is an integer or not, here's my way: if(ereg("^[0-9]+$", $_POST["number"])) $_POST["number"] = (int)$_POST["number"]; In psuedo code: if you are a string full of numbers then convert yourself to an integer So instead of just checking if its a string full of numbers you check and then convert it, which means you can use the standard is_int. You can also do: if(ereg("^[0-9]+$", $_POST["number"])) $_POST["number"] += 0; I think the first way i mentioned is better because your coding what you want to do, rather than the second way that uses a side effect of adding 0 to convert the string. The first way also may make your code ever so slightly faster (nothing noticeable) as php does not need to add 0 to the number after it converts it. Also note an integer is full numbers (1, 2, 3 etc) not decimal numbers (1.1, 2.4, 3.7 etc), to convert decimal numbers you could use something like: if(ereg("^[.0-9]+$", $_POST["number"])) $_POST["number"] = (float)$_POST["number"]; OR if(ereg("^[.0-9]+$", $_POST["number"])) $_POST["number"] += 0; But note that these would not work with is_int(), because they are not integers. tiberiu
You can use this: <?php $result = ((int)$x.""==$x.""); ?> phpguru
To Logan: There's also a simple non-regexp way to convert a (form) value into an integer if it consists of numbers only - although with a trap (see below): if ($_POST["number"] == (int)$_POST["number"]) $_POST["number"] = (int)$_POST["number"]; The "traps" (or "side effects") appear with values like "" (empty string) and false (boolean), which are converted to 0 (integer). But in certain cases this might be desirable or/and usefull ;-) Solutions like if (($_POST["number"] + 1 - 1) == $_POST["number"]) ... falls into the same category. tudor
Please note this from the Integer datatype page: "The size of an integer is platform-dependent, although a maximum value of about two billion is the usual value (that's 32 bits signed). PHP does not support unsigned integers. Integer size can be determined from PHP_INT_SIZE, maximum value from PHP_INT_MAX since PHP 4.4.0 and PHP 5.0.5." This is particularly important if you are doing validation of large keys or any number larger than 2,000,000,000 (e.g. telephone numbers) mark
Or you could just use is_numeric() I have a file called input.php which I run at the beginning of all my scripts which makes sure all my input numbers are converted to integers automatically. if ($_GET) { foreach ($_GET as $k => $v) { $_GET[$k] = trim (stripslashes ($v)); if (is_numeric ($v)) { $_GET[$k] = intval ($v); } } } if ($_POST) { foreach ($_POST as $k => $v) { $_POST[$k] = trim (stripslashes ($v)); if (is_numeric ($v)) { $_POST[$k] = intval ($v); } } } if ($_COOKIE) { foreach ($_COOKIE as $k => $v) { $_COOKIE[$k] = trim (stripslashes ($v)); if (is_numeric ($v)) { $_COOKIE[$k] = intval ($v); } } } ludvig dot ericson
I would like to say that is_int() is pretty helpfull when looking for neat proper ways to check functions that return either integers or booleans (false) on failure (strpos, socket_select, etc.) <?php function mySelect() { global $someSockets; $ret = socket_select($someSockets, $o = array(), $e = array(), 0); if (!$ret) return is_int($ret); /* FURTHER PROCESSING HERE */ return true; // Return true if the function proceeded as expected. } ?> The point of doing this is that if you put this in a while() loopo, you'll break it when the select fails. <?php while (mySelect()); ?> Hope you get the point - toxik lclkk
I think the function below is a robust test for integers working on all datatypes. It works by first checking that a number can be evaluated numerically, and then secondly that the integer evaluation matches the original number. Test cases are included. <? function myIsInt ($x) { return (is_numeric($x) ? intval($x) == $x : false); } function Test($x) { echo "$x is " . ( myIsInt($x) ? ('an integer. The integer value is ' . intval($x)) : 'not an integer.'); echo "\n"; } echo "These should be integers...\n"; Test(1); Test(5); Test(10); Test(10.0); Test(20.0); Test(-20.0); Test(0+4+4.5+4.5); Test("10.0"); Test("+14"); Test("-15"); Test("0"); echo "\nThese should not be integers...\n"; Test(true); // watch out, this displays as '1' Test(false); Test("moose"); Test("3.5"); Test("-214235.5"); Test(""); // empty string Test(array(1,2,3)); Test(dir('.')); // object Test(null); ?> ender
Be aware that is_numeric (mentioned in this article as the proper way to validate string numbers) also allows numbers in scientific and hexadecimal annotation. Thus DO NOT USE that function to validate user input that will be used as id number for in a query for example, this could cause mysql errors. Use ctype_digit instead.
gabe
Although this can be inferred from the documentation, beware of numeric strings. I ran into the problem in a MySQL app where I would either SELECT an INT PRIMARY KEY or INSERT a new record and use mysql_insert_id() to get the KEY before continuing onto the new section. I used is_int() to make sure the subsequent queries wouldn't break when using the key variable. Unfortunately I failed to realize that while mysql_insert_id() returns an int, mysql_result() always returns a string even if you are SELECTing from an INT field. Spent at least 30 minutes trying to figure out why existing records weren't getting linked, but new records would link fine. I ended up using intval() on mysql_result() to make sure subsequent queries still always work. |
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debug_zval_dump doubleval empty floatval get_defined_vars get_resource_type gettype import_request_variables intval is_array is_binary is_bool is_buffer is_callable is_double is_float is_int is_integer is_long is_null is_numeric is_object is_real is_resource is_scalar is_string is_unicode isset print_r serialize settype strval unserialize unset var_dump var_export |
