What is the regex for positive integer?

The regex pattern for positive integer is `^[1-9]\d*$`. This pattern validates integers greater than zero (no leading zeros).

How do I use this regex in JavaScript?

In JavaScript, create the regex with `const regex = /^[1-9]\d*$/;` and test with `regex.test(yourValue)`. It returns `true` if the value matches.

How do I use this regex in Python?

In Python, use `import re; re.match(r'^[1-9]\d*$', value)`. The raw string prefix (`r`) prevents Python from interpreting backslashes as escape characters.

Is this regex case-sensitive?

By default, yes. To make it case-insensitive, add the `i` flag in JavaScript (`/^[1-9]\d*$/i`) or use `re.IGNORECASE` in Python.

Regex for Positive Integer

Regex Pattern

^[1-9]\d*$

Integers greater than zero (no leading zeros)

Quick Answer

The regex pattern for positive integer is `^[1-9]\d*$`. Integers greater than zero (no leading zeros). This works in JavaScript, Python, Ruby, PHP, Java, and most regex engines that support PCRE syntax.

Test Examples

Input	Result
1	✓ Matches
42	✓ Matches
12345	✓ Matches
999999	✓ Matches
0	✗ No match
-1	✗ No match
1.5	✗ No match
01	✗ No match

Code Examples

javascript

const regex = /^[1-9]\d*$/;
const isValid = regex.test(value);

python

import re
pattern = r'^[1-9]\d*$'
if re.match(pattern, value):
    print("valid")

ruby

pattern = /^[1-9]\d*$/
if value =~ pattern
  puts "valid"
end

php

if (preg_match('/^[1-9]\d*$/', $value)) {
    echo "valid";
}

java

String pattern = "^[1-9]\\d*$";
boolean isValid = value.matches(pattern);

Frequently Asked Questions

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RFC 5322 compliant email validation with label length limits