nilaoda/N_m3u8DL-RE · error · ArgumentException

Bad format!

Error message

Bad format!

What it means

CommandInvoker parses a user-supplied range string (e.g. segment index ranges for --select-segments) by splitting on '-'. If the string does not contain exactly one '-' separated into two parts, the parser cannot interpret it as a range and throws ArgumentException("Bad format!"). The caller's catch block converts this into a parse error entry.

Solutions

1. Supply the value as START-END, e.g. "0-100".
2. Use open-ended forms like "-100" or "100-" only if supported (they still need exactly one '-')
3. Remove any extra '-' characters or numeric-range commas from the input.
4. Check the option's help text for the accepted range syntax.

Example fix

// before
var seg = "12"; // single index, no dash
// after
var seg = "12-12"; // explicit range selecting segment 12

var parts = input.Split('-');
if (parts.Length != 2) throw new FormatException($"Expected START-END, got '{input}'");

bool IsValidRange(string s) => !string.IsNullOrEmpty(s) && s.Split('-').Length == 2;

try { ParseRange(input); }
catch (ArgumentException ex) { Console.Error.WriteLine($"Invalid range '{input}': use START-END"); }

When it happens

Trigger: Calling the range parser (via command-line parsing of a range option) with a string like "5", "1-2-3", "abc", or an empty-ish string with no '-'; only 'a-b' with exactly two parts passes.

Common situations: Users type a single segment index instead of a range, use the wrong separator (comma, colon), copy an index list from elsewhere, or include extra dashes.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• Parse Argument [ ] failed!
• Invalid Speed Limit
• must be valid 16-byte HEX or Base64. Input string
• Input must be KEY or KID:KEY format.
• MuxAfterDone disabled, MuxImports not allowed!

AI-assisted analysis of nilaoda/N_m3u8DL-RE@e113dee70c (2026-09-13). Data as JSON: /api/errors/e3953dd6774390a3. Report an issue: GitHub.

Appendix: source

Thrown at src/N_m3u8DL-RE/CommandLine/CommandInvoker.cs:161

    /// <summary>
    /// 解析用户定义的下载范围
    /// </summary>
    /// <param name="result"></param>
    /// <returns></returns>
    /// <exception cref="ArgumentException"></exception>
    private static CustomRange? ParseCustomRange(ArgumentResult result)
    {
        var input = result.Tokens[0].Value;
        // 支持的种类 0-100; 01:00:00-02:30:00; -300; 300-; 05:00-; -03:00;
        try
        {
            if (string.IsNullOrEmpty(input))
                return null;

            var arr = input.Split('-');
            if (arr.Length != 2)
                throw new ArgumentException("Bad format!");

            if (input.Contains(':'))
            {
                return new CustomRange()
                {
                    InputStr = input,
                    StartSec = arr[0] == "" ? 0 : OtherUtil.ParseDur(arr[0]).TotalSeconds,
                    EndSec = arr[1] == "" ? double.MaxValue : OtherUtil.ParseDur(arr[1]).TotalSeconds,
                };
            }

            if (RangeRegex().IsMatch(input))
            {
                var left = RangeRegex().Match(input).Groups[1].Value;
                var right = RangeRegex().Match(input).Groups[2].Value;
                return new CustomRange()
                {
                    InputStr = input,

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