FILTER_VALIDATE_FLOAT to validate FLOAT data of a variable in PHP

Validate floating-point input

FILTER_VALIDATE_FLOAT checks whether a value is a valid floating-point number. Use options and flags only when the input rules require them.

$value = '19.75';
$result = filter_var($value, FILTER_VALIDATE_FLOAT);
var_dump($result);

$price=12.32; // Change this value to get different result
if(filter_var($price,FILTER_VALIDATE_FLOAT)){
echo " Yes validation passed ";
}else{
echo " No validation failed ";
}

By using FILTER_VALIDATE_FLOAT we can validate variables to check if float data is present or not.
By using filter id of FILTER_VALIDATE_FLOAT the above script can be written as

if(filter_var($price,259)){

Difference between FILTER_VALIDATE_FLOAT and FILTER_VALIDATE_INT

$var=12.34;
if(filter_var($var, FILTER_VALIDATE_FLOAT)){
echo "Yes true for FILTER_VALIDATE_FLOAT: $var";
}else{
echo "No false FILTER_VALIDATE_FLOAT: $var";
}

Output is

Yes true for FILTER_VALIDATE_FLOAT: 12.34

Now using FILTER_VALIDATE_INT

$var=12.34;
if(filter_var($var, FILTER_VALIDATE_INT)){
echo "Yes true for FILTER_VALIDATE_INT: $var";
}else{
echo "No false FILTER_VALIDATE_INT: $var";
}

Output is

No false FILTER_VALIDATE_INT: 12.34

Maximum and minimum range

$price=12.32; // Change this value to get different result
if(filter_var($price,FILTER_VALIDATE_FLOAT,
	["options" => ["max_range" => 13.2,"min_range"=>11.2]])){
echo " Yes validation passed ";
}else{
echo " No validation failed ";
}

Output

Yes validation passed

Example : Validating and Sanitizing a Float Input

This example demonstrates how to validate and sanitize a float value:

$input = "23.45abc";
$sanitized_input = filter_var($input, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_FRACTION);
if (filter_var($sanitized_input, FILTER_VALIDATE_FLOAT)) {
    echo "Valid float: " . $sanitized_input;
} else {
    echo "Invalid float.";
}

Example : Handling Scientific Notation in Float Validation

You can also validate scientific notation using FILTER_VALIDATE_FLOAT:

$input = "4.56e2";
if (filter_var($input, FILTER_VALIDATE_FLOAT)) {
    echo "Valid float in scientific notation.";
} else {
    echo "Invalid float.";
}

Filter reference Validating Boolean data Ctype_alnum to check alphanumeric characters Validating Email address

Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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