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Sometimes we need to validate an input from client browser before we push the value into further proccess, here i share 3 simple functions to perform validation input from forms and or querrystrings

Validate Integer Value Using isNumeric function

function isNumeric($n){
return ( $n == strval(intval($n)) )? true : false;
}

the simple php function above will perform an integer validation input, the proccess is pretty simple, the if control structure will evaluate whether the argument value ($n) has the same type with itself after cast to integer (strval(intval($n))), the right part of if expression (strval(intval($n))) is a simple way to cast any type of variable into integer. Sample of usage:

echo ‘ isNumeric(1) = ‘.(string)isNumeric(1);
echo ‘ isNumeric("a") = ‘.(string)isNumeric(‘a’);
echo ‘ isNumeric(0.1) = ‘.(string)isNumeric(0.1);

Validate Float Value Using isFloat function

function isFloat($n){
return ( $n == strval(floatval($n)) )? true : false;
}

the simple php function above has same proccess with isNumeric function the difference is only the second part of if expression (strval(floatval($n))) which has function to cast the value of argument into floating point variable. Sample of usage:

echo ‘ isFloat(1) = ‘.(string)isFloat(1);
echo ‘ isFloat("a") = ‘.(string)isFloat(‘a’);
echo ‘ isFloat(0.1) = ‘.(string)isFloat(0.1);

Validate Characters Length Using isLength function

function isLength($s,$min,$max){
$curLength = strlen($s);
return (($curLength >= (int)($min)) && ($curLength <= (int)($max)))? true : false;
}

the php function above will perform a Length of characters validation, it takes 3 arguments which are (string_to_be_validate,minimum_length,maximum_length). Sample of usage:

echo ‘ isLength("aku",1,4) = ‘.isLength(‘aku’,1,4);
echo ‘ isLength("aku",4,4) = ‘.isLength(‘aku’,4,4);
echo ‘ isLength("aku",3,4) = ‘.isLength(‘aku’,3,4);