Regex to Match an Integer
Copy the pattern, paste your text below, and see every whole number it finds. Below the tester: how to keep it from matching parts of decimals, and how to require a full-string match.
What this pattern matches
This expression matches whole numbers, positive or negative: 42, -7, 1000. It uses word boundaries so it grabs complete numbers rather than random digits inside longer tokens.
How it works, part by part
-? — an optional leading minus sign.
\b — a word boundary so the match starts at the beginning of a number.
\d+ — one or more digits.
\b — a closing word boundary.
Integers inside decimals
In free text, 3.14 contains the integers 3 and 14, and this pattern will match both. If you want only standalone integers and not the pieces of a decimal, use a lookahead like -?\b\d+\b(?!\.\d). To validate that an entire string is a single integer, anchor it: ^-?\d+$.
Use it in your code
import re
text = "Order 42 units at -7 discount, total 1000. A decimal 3.14 has an integer part 3 and 14."
pattern = r'''-?\b\d+\b'''
for m in re.finditer(pattern, text):
print(m.group())const text = "Order 42 units at -7 discount, total 1000. A decimal 3.14 has an integer part 3 and 14.";
const re = new RegExp(String.raw`-?\b\d+\b`, "g");
console.log(text.match(re));FAQ
Does it match a leading plus sign like +5?
No. Change -? to [-+]? to allow an optional plus or minus.
Why does it match 3 and 14 inside 3.14?
It only knows digits and word boundaries, not decimal points. Add (?!\.\d) to skip integers that are part of a decimal.
How do I require the whole string to be an integer?
Anchor it with ^-?\d+$ so nothing but an integer is allowed from start to end.