I'm currently having issues parsing some numbers starting with 0 in Go.

fmt.Println(strconv.ParseInt("0491031", 0, 64))

0 strconv.ParseInt: parsing "0491031": invalid syntax

GoPlayground: https://go.dev/play/p/TAv7IEoyI8I

I think this is due to some base conversion error, but I don't have ideas about how to fix it. I'm getting this error parsing a 5GB csv file with gocsv, if you need more details.

CodePudding user response：

Quoting from strconv.ParseInt()

If the base argument is 0, the true base is implied by the string's prefix following the sign (if present): 2 for "0b", 8 for "0" or "0o", 16 for "0x", and 10 otherwise. Also, for argument base 0 only, underscore characters are permitted as defined by the Go syntax for integer literals.

You are passing 0 for base, so the base to parse in will be inferred from the string value, and since it starts with a '0' followed by a non '0', your number is interpreted as an octal (8) number, and the digit 9 is invalid there.

Note that this would work:

fmt.Println(strconv.ParseInt("0431031", 0, 64))

And output (try it on the Go Playground):

143897 <nil>

(Octal 431031 equals 143897 decimal.)

If your input is in base 10, pass 10 for base:

fmt.Println(strconv.ParseInt("0491031", 10, 64))

Then output will be (try it on the Go Playground):

491031 <nil>