I am working in PHP and I want to check if a given user submitted numeric input is not too big or too small.
I am storing the amounts in the database as 64 bit integers (multiply them by 10^8 to avoid rounding errors in future calculations). I am limiting the amounts so that they cannot exceed the following precision: no more than 4 numbers after the decimal point. Also since the upper limit on user input should be 99 million, I also want to specify no more than 8 numbers precending the decimal point. How can I achieve this neatly?
My current approach seems a bit hack-ish:
Code:
//Check for existence of decimal point in string using strpos
//explode the string by the decimal point
//do a strlen on both the strings and check they dont exceed 8 and 4 respectively
//if no decimal point, simply do a strelen and check it's not greater than 8
Also, I don't want the inputted data to be smaller than 0.0001. I am proficient in php for web design not familiar with the math functions of php is there an easy way to handle this?
Thanks for any tips
Using the code below you can check whether the $input conforms to your requirements.
(See also this short demo.)
$input = ...;
$pattern = "~^\s*\d{1,8}(?:\.\d{1,4})?\s*$~";
if (($input > 0) && preg_match($pattern, $input)) {
/* $input is OK */
} else {
/* $input is NOT OK */
}
Requirements:
$input has an integral part that is between 1 and 8 digits long.
$input optionally contains a . followed by 1 to 4 digits (fractional part).
$input is a positive number greater than or equal to 0.0001.
You can use regular expressions and the mb_ereg_match(regex,string) function
you can try this:
if (preg_match('~^(?>[1-9]\d{0,7}+|0)(?>\.\d{0,3}+[1,9])?$~', trim($number), $result))
// true
else
// false
This pattern avoids things like 00015 or 1.000, but if you want to allow this, just replace [1-9] by \d or better use ~^\d{1,8}+(?>\.\d{1,4}+)?$~ instead.
You must work after with $result which contain the trimed and verified number.
I think the following regex will match your needs.
It will match all numbers between 99999999.9999 and 00000000.0000 with and without the decimal point and also empty string.
The fractal part contains no more than 4 digits
if (preg_match('~^[0..9]{0,8}(?:\.[0..9]{1,4})?$~'), $number) {
$match = TRUE;
} else{
$match = FALSE;
}
See if this works:
$number = '123.4567';
if(preg_match('/^\s*\d*\.?\d{4}\s*$/', $number)) echo "Match";
else echo "Not match";
Related
I need to be able to search within a string and find out if [topic] is equal to a number and grab that number only from within the string.
For example, a string like so:
[topic]=10[board]=1
should return 10
But a string like this:
[topic][board]=1
should return 0 or false
A string like this:
[topic]=1.5[board]=2
should return 1, cause we need to round down floor()
Also, we aren't worried about negative numbers, cause this will never happen.
How can I do this to just grab the number only, rounding down, from these types of strings that look like this, only if [topic] is present in the string and defined with an equal sign.
Thanks guys :)
The idea below uses preg_match and a regular express that looks for the word "topic" inside square brackets followed by an equal sign and one of more numbers. Before the matches, I set the default value of the topic (false in this case). If a topic is found, I then convert it to an integer.
This will ignore the decimal point and any numbers that follow as \d only contains the numbers 0 through 9.
Example:
<?php
$string = '[topic]=10[board]=1';
$topic = false;
if (preg_match('/\[topic\]=(?P<topic>\d+)/', $string, $matches)) {
$topic = (int)$matches['topic'];
}
var_dump($topic);
This isn't a big issue for me (as far as I'm aware), it's more of something that's interested me. But what is the main difference, if any, of using is_numeric over preg_match (or vice versa) to validate user input values.
Example One:
<?php
$id = $_GET['id'];
if (!preg_match('/^[0-9]*$/', $id)) {
// Error
} else {
// Continue
}
?>
Example Two:
<?php
$id = $_GET['id'];
if (!is_numeric($id)) {
// Error
} else {
// Continue
}
?>
I assume both do exactly the same but is there any specific differences which could cause problems later somehow? Is there a "best way" or something I'm not seeing which makes them different.
is_numeric() tests whether a value is a number. It doesn't necessarily have to be an integer though - it could a decimal number or a number in scientific notation.
The preg_match() example you've given only checks that a value contains the digits zero to nine; any number of them, and in any sequence.
Note that the regular expression you've given also isn't a perfect integer checker, the way you've written it. It doesn't allow for negatives; it does allow for a zero-length string (ie with no digits at all, which presumably shouldn't be valid?), and it allows the number to have any number of leading zeros, which again may not be the intended.
[EDIT]
As per your comment, a better regular expression might look like this:
/^[1-9][0-9]*$/
This forces the first digit to only be between 1 and 9, so you can't have leading zeros. It also forces it to be at least one digit long, so solves the zero-length string issue.
You're not worried about negatives, so that's not an issue.
You might want to restrict the number of digits, because as things stand, it will allow strings that are too big to be stored as integers. To restrict this, you would change the star into a length restriction like so:
/^[1-9][0-9]{0,15}$/
This would allow the string to be between 1 and 16 digits long (ie the first digit plus 0-15 further digits). Feel free to adjust the numbers in the curly braces to suit your own needs. If you want a fixed length string, then you only need to specify one number in the braces.
According to http://www.php.net/manual/en/function.is-numeric.php, is_numeric alows something like "+0123.45e6" or "0xFF". I think this not what you expect.
preg_match can be slow, and you can have something like 0000 or 0051.
I prefer using ctype_digit (works only with strings, it's ok with $_GET).
<?php
$id = $_GET['id'];
if (ctype_digit($id)) {
echo 'ok';
} else {
echo 'nok';
}
?>
is_numeric() allows any form of number. so 1, 3.14159265, 2.71828e10 are all "numeric", while your regex boils down to the equivalent of is_int()
is_numeric would accept "-0.5e+12" as a valid ID.
Not exactly the same.
From the PHP docs of is_numeric:
'42' is numeric
'1337' is numeric
'1e4' is numeric
'not numeric' is NOT numeric
'Array' is NOT numeric
'9.1' is numeric
With your regex you only check for 'basic' numeric values.
Also is_numeric() should be faster.
is_numeric checks whether it is any sort of number, while your regex checks whether it is an integer, possibly with leading 0s. For an id, stored as an integer, it is quite likely that we will want to not have leading 0s. Following Spudley's answer, we can do:
/^[1-9][0-9]*$/
However, as Spudley notes, the resulting string may be too large to be stored as a 32-bit or 64-bit integer value. The maximum value of an signed 32-bit integer is 2,147,483,647 (10 digits), and the maximum value of an signed 64-bit integer is 9,223,372,036,854,775,807 (19 digits). However, many 10 and 19 digit integers are larger than the maximum 32-bit and 64-bit integers respectively. A simple regex-only solution would be:
/^[1-9][0-9]{0-8}$/
or
/^[1-9][0-9]{0-17}$/
respectively, but these "solutions" unhappily restrict each to 9 and 19 digit integers; hardly a satisfying result. A better solution might be something like:
$expr = '/^[1-9][0-9]*$/';
if (preg_match($expr, $id) && filter_var($id, FILTER_VALIDATE_INT)) {
echo 'ok';
} else {
echo 'nok';
}
is_numeric checks more:
Finds whether the given variable is numeric. Numeric strings consist
of optional sign, any number of digits, optional decimal part and
optional exponential part. Thus +0123.45e6 is a valid numeric value.
Hexadecimal notation (0xFF) is allowed too but only without sign,
decimal and exponential part.
You can use this code for number validation:
if (!preg_match("/^[0-9]+$/i", $phone)) {
$errorMSG = 'Invalid Number!';
$error = 1;
}
If you're only checking if it's a number, is_numeric() is much much better here. It's more readable and a bit quicker than regex.
The issue with your regex here is that it won't allow decimal values, so essentially you've just written is_int() in regex. Regular expressions should only be used when there is a non-standard data format in your input; PHP has plenty of built in validation functions, even an email validator without regex.
PHP's is_numeric function allows for floats as well as integers. At the same time, the is_int function is too strict if you want to validate form data (strings only). Therefore, you had usually best use regular expressions for this.
Strictly speaking, integers are whole numbers positive and negative, and also including zero. Here is a regular expression for this:
/^0$|^[-]?[1-9][0-9]*$/
OR, if you want to allow leading zeros:
/^[-]?[0]|[1-9][0-9]$/
Note that this will allow for values such as -0000, which does not cause problems in PHP, however. (MySQL will also cast such values as 0.)
You may also want to confine the length of your integer for considerations of 32/64-bit PHP platform features and/or database compatibility. For instance, to limit the length of your integer to 9 digits (excluding the optional - sign), you could use:
/^0$|^[-]?[1-9][0-9]{0,8}$/
Meanwhile, all the values above will only restrict the values to integer,
so i use
/^[1-9][0-9\.]{0,15}$/
to allow float values too.
You can use filter_var() to check for integers in strings
<?php
$intnum = "1000022";
if (filter_var($intnum, FILTER_VALIDATE_INT) !== false){
echo $intnum.' is an int now';
}else{
echo "$intnum is not an int.";
}
// will output 1000022 is an int now
I want to make a bid system on a website. That means users can post their bid (natural number). I want to make sure users don't try to post characters, decimal numbers, etc.
I don't want to use is_numeric function because hexadecimal notation is allowed.
I was thinking to use preg_match for this. But in php.net the documentation for this function is little and I have no idea how to use preg_match.
So how should I check if a variable is a natural number with preg_match?
If you don't require decimal points: ctype_digit or filter_var($var, FILTER_VALIDATE_INT).
If you do: filter_var($var, FILTER_VALIDATE_FLOAT).
ctype_digit does what you want:
Checks if all of the characters in the provided string, text, are numerical.
(Before PHP 5.1.0, this function returned TRUE when text was an empty string.)
Either preg_match('/^[0-9]+$/', $var); or ctype_digit
I would generally caution against using regex for parsing numerics, as there are generally better solutions than regex for this, but since you're asking, I'll try to give you some assistance with it:
preg_match uses regular expressions (regex) for it's matching.
You can find out more about regex syntax at sites like http://www.regular-expressions.info/
If you want to match a digit in regex, you can either use [0-9] or \d.
If you want to match one or more of anything, you would use a plus sign.
Finally, regex strings need to be enclosed in a pair of characters. The character chosen is usually a slash (/) character, as some languages specifically require this character, but PHP also allows other characters to be used; tilde (~) is quite common.
So your regex string to match any number of digits would be "/\d+/". This can then be put into a preg_match call like so:
$isnumeric = preg_match("/\d+/",$input_string);
If you have more specific requirements, you can limit the number of characters allowed by replacing the plus sign with {max} or {min,max} where 'min' and 'max' are the number of times the preceding match is allowed. So to allow a number between two and six digits long, you would use this:
$isnumeric = preg_match("/\d{2,6}/",$input_string);
If you need to allow a decimal point, you need to know that the dot character is a special character in regex (it means 'match any character at all'), so you need to escape it with a back-slash.
Therefore, a regex to match a currency amount with two decimal places, and at least one digit before the point would be like this:
$isnumeric = preg_match("/\d+\.\d\d/",$input_string);
Finally, note that regex will return true in all the above if the string simply contains the matched value. To ensure it doesn't contain anything else, you would need to 'anchor' it to the front and end of the string, using the anchor characters: ^ for the start of the string, and $ for the end.
So for the previous example, if you want it to only contain a decimal number, and nothing else, you would need this:
$isnumeric = preg_match("/^\d+\.\d\d$/",$input_string);
Regex is a complex subject, but I hope that gives you a start.
I know this is very old but I wanted to share the next solution in case someone else comes up with this problem.
I'm assuming that by natural number you meant positive integer (which excludes the number 0).
function is_positive_integer( $value ) {
// Check if is integer and greater than zero
if( is_int( $value ) && $value > 0 ) {
return true;
}
// Is not a positive integer
else {
return false;
}
}
This kind of depends on your definition of natural numbers - according to different theories, the number zero (0) does or does not count as a natural number.
To answer your question on how to solve this with preg_match:
If you want to include zero, using preg_match is pretty easy preg_match('^[0-9]+$', $input).
Usage:
if (preg_match('^[0-9]+$', $input))
// $input represents a non-negative numeric value
else
// $input does not represent a non-negative numeric value
If you don't want to include the zero, use preg_match('^[1-9][0-9]*$', $input):
if (preg_match('^[1-9][0-9]*$', $input))
// $input represents a positive numeric value
else
// $input does not represent a positive numeric value
That said - for your particular problem, using ctype_digit is a faster solution, as others already pointed out (you'd have to do a second check if you don't want to allow the number zero).
in_array(str_replace(str_split('0123456789'), '', $s), array(',','.',''));
simple function:
function isnature($x){
$y = ceil($x)-floor($x);
return $y == 0 ? true : false;
}
From a mathematical point of view, a natural number is a positive integer, including zero, so you could check it like this:
is_int($bid) && $bid >= 0
Simplest and faster
if( is_numeric( $key ) && intval( $key ) == $key )
{
//key == number
}
This question already has answers here:
How to validate phone numbers using regex
(43 answers)
Closed 9 years ago.
How to validate phone number using php
Here's how I find valid 10-digit US phone numbers. At this point I'm assuming the user wants my content so the numbers themselves are trusted. I'm using in an app that ultimately sends an SMS message so I just want the raw numbers no matter what. Formatting can always be added later
//eliminate every char except 0-9
$justNums = preg_replace("/[^0-9]/", '', $string);
//eliminate leading 1 if its there
if (strlen($justNums) == 11) $justNums = preg_replace("/^1/", '',$justNums);
//if we have 10 digits left, it's probably valid.
if (strlen($justNums) == 10) $isPhoneNum = true;
Edit: I ended up having to port this to Java, if anyone's interested. It runs on every keystroke so I tried to keep it fairly light:
boolean isPhoneNum = false;
if (str.length() >= 10 && str.length() <= 14 ) {
//14: (###) ###-####
//eliminate every char except 0-9
str = str.replaceAll("[^0-9]", "");
//remove leading 1 if it's there
if (str.length() == 11) str = str.replaceAll("^1", "");
isPhoneNum = str.length() == 10;
}
Log.d("ISPHONENUM", String.valueOf(isPhoneNum));
Since phone numbers must conform to a pattern, you can use regular expressions to match the entered phone number against the pattern you define in regexp.
php has both ereg and preg_match() functions. I'd suggest using preg_match() as there's more documentation for this style of regex.
An example
$phone = '000-0000-0000';
if(preg_match("/^[0-9]{3}-[0-9]{4}-[0-9]{4}$/", $phone)) {
// $phone is valid
}
I depends heavily on which number formats you aim to support, and how strict you want to enforce number grouping, use of whitespace and other separators etc....
Take a look at this similar question to get some ideas.
Then there is E.164 which is a numbering standard recommendation from ITU-T
I have database records in the form of 10 character long strings, such as 4085551234.
I wish to format these into this format: (408) 555-1234.
I think this is regex related. I'm new to programming and completely self-taught here, so any sort of resource relating to performing text processing would be appreciated as well. Thanks!
A regex is definitely overkill for this one. If you wanted to take a "phone number" and normalize it to 10 digits, that would be a good use for a regex. To do what you're asking, just do something like:
echo '('.substr($data, 0, 3).') '.substr($data, 3, 3).'-'.substr($data,6);
Since you already know how to divide up your data, you can just use substr or something similar to grab the parts you want. RegEx is useful for matching strings which don't always have a strict format. (Like variable numbers of spaces, variable stuff before or after it, extra dashes, etc). But in your case the input is always strictly formatted 10 digits, nothing else, so you don't need the extra overhead of a RegEx to format it.
Take a look here: Format phone number
function format_phone($phone)
{
$phone = preg_replace("/^\d/", "", $phone);
if(strlen($phone) == 7)
return preg_replace("/(\d{3})(\d{4})/", "$1-$2", $phone);
elseif(strlen($phone) == 10)
return preg_replace("/(\d{3})(\d{3})(\d{4})/", "($1) $2-$3", $phone);
else
return $phone;
}
I'd probably go with
$num = "4085551234"; // given
$formatted = "(".substr($num,0,3).") ".substr($num,3,3)."-".substr($num,6);
Regex isn't really appropriate here.
Trivially you could do something like:
\(\d\{3\}\)\(\d\{3\}\)\(\d\{4\}\)
To match the 10 digits into 3 subgroup expressions, and then print them out using each subgroup:
"(\1) \2-\3
But in practice free form data is usually a little trickier
I had to do this question for my advanced placement computer science class.
Java:
Write a program that accepts a 10 digit # and formats it as a phone number.
Ex: 705726552
Output: (705)726-2552
import java.util.Scanner;
public class TelNumCorrection{
public static void main(String[]args){
Scanner scan = new Scanner(System.in);
System.out.println("Please enter a 10 digit number");
String num=scan.nextLine();
String a=num.substring(0,3);
String b=num.substring(3,6);
String c=num.substring(6);
System.out.println("("+a+ ")"+b+"-"+c);
}
}