Decimal Number Regex

^-?[0-9]*\.?[0-9]+$

Match decimal numbers with optional negative sign and decimal point.

Test This Pattern →

Pattern Breakdown

Understanding the regex pattern ^-?[0-9]*\.?[0-9]+$:

  • ^ - Start of string
  • $ - End of string
  • ? - Optional (zero or one)
  • + - One or more
  • * - Zero or more
  • [...] - Character class

Examples

Input Result Explanation
123.456 ✓ Match Positive decimal
-0.5 ✓ Match Negative decimal
.5 ✓ Match No leading zero

Code Examples

JavaScript

JavaScript
const pattern = /^-?[0-9]*\.?[0-9]+$/;
const text = "123.456";

// Test if string matches
if (pattern.test(text)) {
  console.log("Valid!");
}

// Extract matches
const matches = text.match(pattern);
console.log(matches);

Python

Python
import re

pattern = r'^-?[0-9]*\.?[0-9]+$'
text = "123.456"

# Test if string matches
if re.match(pattern, text):
    print("Valid!")

# Find all matches
matches = re.findall(pattern, text)
print(matches)

PHP

PHP
<?php
$pattern = '/^-?[0-9]*\.?[0-9]+$/';
$text = "123.456";

// Test if string matches
if (preg_match($pattern, $text)) {
    echo "Valid!";
}

// Find all matches
preg_match_all($pattern, $text, $matches);
print_r($matches);
?>

Java

Java
import java.util.regex.*;

String pattern = "^-?[0-9]*\\.?[0-9]+$";
String text = "123.456";

Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(text);

if (m.matches()) {
    System.out.println("Valid!");
}

Use Cases

Common applications: Scientific data, financial calculations

Frequently Asked Questions

What is the regex pattern for decimal number regex?
The regex pattern is: ^-?[0-9]*\.?[0-9]+$. Match decimal numbers with optional negative sign and decimal point.
How do I use the decimal number regex pattern in JavaScript?
In JavaScript: const regex = new RegExp('^-?[0-9]*\\.?[0-9]+$'); or const regex = /^-?[0-9]*\.?[0-9]+$/;
Does this pattern work in Python?
Yes, use: import re; pattern = re.compile(r'^-?[0-9]*\.?[0-9]+$') in Python. Most regex patterns are cross-language compatible.
What are common use cases for decimal number regex?
Scientific data, financial calculations

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