What causes "wrong input: %q (line #%d)" in inancgumus/learngo?

Fix the offending value in the input log

wrong input: %q (line #%d)

Error message

wrong input: %q (line #%d)

What it means

In v4's Parse, after fields = strings.Fields(line), the second field is converted with strconv.Atoi. If Atoi fails or the visits count is negative, Parse stores 'wrong input: %q (line #%d)' (quoting the visits token and line number) in p.lerr and returns; the result for that line is not passed to update.

Source

Thrown at logparser/v4/parser.go:58

	if p.lerr != nil {
		return
	}

	p.lines++

	fields := strings.Fields(line)
	if len(fields) != 2 {
		p.lerr = fmt.Errorf("wrong input: %v (line #%d)", fields, p.lines)
		return
	}

	var err error

	r.domain = fields[0]
	r.visits, err = strconv.Atoi(fields[1])

	if r.visits < 0 || err != nil {
		p.lerr = fmt.Errorf("wrong input: %q (line #%d)", fields[1], p.lines)
	}
	return
}

// update updates all the parsing results using the given parsing result
func update(p *parser, r result) {
	if p.lerr != nil {
		return
	}

	// Collect the unique domains
	if _, ok := p.sum[r.domain]; !ok {
		p.domains = append(p.domains, r.domain)
	}

	// Keep track of total and per domain visits
	p.total += r.visits

View on GitHub (pinned to 3c475a78e5)

Solutions

Fix the offending value in the input log
Pre-validate the visits token as a non-negative integer
Separate the 'not a number' and 'negative' cases for clearer diagnostics

Example fix

// before
if r.visits < 0 || err != nil {
    p.lerr = fmt.Errorf("wrong input: %q (line #%d)", fields[1], p.lines)
}
// after
if err != nil {
    p.lerr = fmt.Errorf("line #%d: visits %q is not a number", p.lines, fields[1])
} else if r.visits < 0 {
    p.lerr = fmt.Errorf("line #%d: visits %d is negative", p.lines, r.visits)
}

Defensive patterns

Strategy: validation

Validate before calling

var countRe = regexp.MustCompile(`^\d+$`)
fs := strings.Fields(line)
if len(fs) == 2 && !countRe.MatchString(fs[1]) {
    continue // skip non-numeric visits before Parse
}

Type guard

func isNonNegInt(s string) bool {
    n, err := strconv.Atoi(s)
    return err == nil && n >= 0
}

Try / catch

if p.lerr != nil {
    var ne *strconv.NumError
    if errors.As(p.lerr, &ne) { /* not always wrapped; inspect message */ }
    log.Fatalf("parse stopped: %v", p.lerr)
}

Prevention

Validate the visits token before feeding the line to Parse
Split negative vs. non-numeric handling for clearer errors
Check p.lerr after parsing and report the line number
Normalize locale-formatted numbers upstream

When it happens

Trigger: A line whose visits column is negative ('example.com -1') or unparseable ('example.com 12x') during v4 Parse.

Common situations: Negative deltas from upstream aggregation bugs, numbers with units or separators, typos, or locale-formatted numbers ('1.000').

Related errors

AI-assisted analysis of inancgumus/learngo@3c475a78e5 (2026-09-02). Data as JSON: /api/errors/430c4f8e5e417602. Report an issue: GitHub.