使用 Golang regexp 在字符串中查找数字

Question

I want to find all numbers in a string with the following code:

re:=regexp.MustCompile("[0-9]+")
fmt.Println(re.FindAllString("abc123def", 0))

I also tried adding delimiters to the regex, using a positive number as second parameter for FindAllString , using a numbers only string like "123" as first parameter...

But the output is always []

I seem to miss something about how regular expressions work in Go, but cannot wrap my head around it. Is [0-9]+ not a valid expression?

Answer 1

The problem is with your second integer argument. Quoting from the package doc of regex :

These routines take an extra integer argument, n; if n >= 0, the function returns at most n matches/submatches.

You pass 0 so at most 0 matches will be returned; that is: none (not really useful).

Try passing -1 to indicate you want all.

Example:

re := regexp.MustCompile("[0-9]+")
fmt.Println(re.FindAllString("abc123def987asdf", -1))

Output:

[123 987]

Try it on the Go Playground .

Answer 2

@icza answer is perfect for fetching positive numbers but, if you have a string which contains negative numbers also like below

"abc-123def987asdf"

and you are expecting output like below

[-123 987]

replace regex expression with below

re := regexp.MustCompile(`[-]?\d[\d,]*[\.]?[\d{2}]*`)