Essential Books

Sanitize Floats

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Remove all characters except digits, +- and optionally .,eE. 

var_dump(filter_var(1, FILTER_SANITIZE_NUMBER_FLOAT));
var_dump(filter_var(1.0, FILTER_SANITIZE_NUMBER_FLOAT));
var_dump(filter_var(1.0000, FILTER_SANITIZE_NUMBER_FLOAT));
var_dump(filter_var(1.00001, FILTER_SANITIZE_NUMBER_FLOAT));
var_dump(filter_var('1', FILTER_SANITIZE_NUMBER_FLOAT));
var_dump(filter_var('1.0', FILTER_SANITIZE_NUMBER_FLOAT));
var_dump(filter_var('1.0000', FILTER_SANITIZE_NUMBER_FLOAT));
var_dump(filter_var('1.00001', FILTER_SANITIZE_NUMBER_FLOAT));
var_dump(filter_var('1,000', FILTER_SANITIZE_NUMBER_FLOAT));
var_dump(filter_var('1,000.0', FILTER_SANITIZE_NUMBER_FLOAT));
var_dump(filter_var('1,000.0000', FILTER_SANITIZE_NUMBER_FLOAT));
var_dump(filter_var('1,000.00001', FILTER_SANITIZE_NUMBER_FLOAT));
var_dump(filter_var('1.8281e-009', FILTER_SANITIZE_NUMBER_FLOAT));

Results: 

string(1) "1"
string(1) "1"
string(1) "1"
string(6) "100001"
string(1) "1"
string(2) "10"
string(5) "10000"
string(6) "100001"
string(4) "1000"
string(5) "10000"
string(8) "10000000"
string(9) "100000001"
string(9) "18281-009"

With the FILTER_FLAG_ALLOW_THOUSAND option: 

var_dump(filter_var(1, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_THOUSAND));
var_dump(filter_var(1.0, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_THOUSAND));
var_dump(filter_var(1.0000, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_THOUSAND));
var_dump(filter_var(1.00001, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_THOUSAND));
var_dump(filter_var('1', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_THOUSAND));
var_dump(filter_var('1.0', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_THOUSAND));
var_dump(filter_var('1.0000', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_THOUSAND));
var_dump(filter_var('1.00001', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_THOUSAND));
var_dump(filter_var('1,000', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_THOUSAND));
var_dump(filter_var('1,000.0', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_THOUSAND));
var_dump(filter_var('1,000.0000', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_THOUSAND));
var_dump(filter_var('1,000.00001', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_THOUSAND));
var_dump(filter_var('1.8281e-009', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_THOUSAND));

Results: 

string(1) "1"
string(1) "1"
string(6) "100001"
string(1) "1"
string(2) "10"
string(5) "10000"
string(6) "100001"
string(5) "1,000"
string(6) "1,0000"
string(9) "1,0000000"
string(10) "1,00000001"
string(9) "18281-009"

With the FILTER_FLAG_ALLOW_SCIENTIFIC option: 

var_dump(filter_var(1, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_SCIENTIFIC));
var_dump(filter_var(1.0, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_SCIENTIFIC));
var_dump(filter_var(1.0000, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_SCIENTIFIC));
var_dump(filter_var(1.00001, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_SCIENTIFIC));
var_dump(filter_var('1', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_SCIENTIFIC));
var_dump(filter_var('1.0', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_SCIENTIFIC));
var_dump(filter_var('1.0000', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_SCIENTIFIC));
var_dump(filter_var('1.00001', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_SCIENTIFIC));
var_dump(filter_var('1,000', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_SCIENTIFIC));
var_dump(filter_var('1,000.0', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_SCIENTIFIC));
var_dump(filter_var('1,000.0000', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_SCIENTIFIC));
var_dump(filter_var('1,000.00001', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_SCIENTIFIC));
var_dump(filter_var('1.8281e-009', FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_SCIENTIFIC));

Results: 

string(1) "1"
string(1) "1"
string(1) "1"
string(6) "100001"
string(1) "1"
string(2) "10"
string(5) "10000"
string(6) "100001"
string(4) "1000"
string(5) "10000"
string(8) "10000000"
string(9) "100000001"
string(10) "18281e-009"
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Filters, filter functions:
* Filters Filter Functions
* Validate Email Address
* Validating A Value Is An Integer
* Validating An Integer Falls In A Range
* Validate a URL
* Sanitize filters
* Validating Boolean Values
* Validating A Number Is A Float
* Validate A MAC Address
* Sanitze Email Addresses
* Sanitize Integers
* Sanitize URLs
* Sanitize Floats
* Validate IP Addresses
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