Comma-Separated Values (.csv)
RFC StandardComma-Separated Values (CSV) is a ubiquitous plain-text format for tabular data, where each line represents a data record and fields are separated by delimiter characters.
Konvertera XLSX till CSV
Gratis konverterare från XLSX till CSV i webbläsaren. Konvertera filer direkt på din enhet.
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Granska & Metadata
Operativsystem och filanalysverktyg identifierar CSV-filer genom att granska den inledande binära bytesekvensen:
Signatur för filhuvud på bytenivå (Magic Bytes)
Operativsystem och filanalysverktyg identifierar CSV-filer genom att granska den inledande binära bytesekvensen:
HEX-SIGNATUR (OFFSET 0):
Plain TextASCII-REPRESENTATION: ASCII / UTF-8
Standardisering: RFC 4180 / IETF
Tekniska specifikationer
| Containerarkitektur | Delimited flat text file representing tabular data rows and columns |
| Komprimering | Gzip / Deflate achieves 85%-95% compression on repetitive tabular records |
| Bytessordinning | UTF-8 text stream (optional UTF-8 BOM EF BB BF used by Excel) |
| Färgrymder | Not applicable |
| Kanaler och struktur | Row records delimited by CRLF with columns delimited by commas |
| Maximala dimensioner | Unbounded; streamable to gigabytes without loading entire file in memory |
| Transparens | Not applicable |
| Strömning och progressiv | Native line-by-line stream processing supported by all data pipelines |
Teknisk jämförelsematris: CSV vs konkurrenter
| Tekniskt attribut | CSV (Aktuell) | Excel (XLSX) | Parquet | JSON |
|---|---|---|---|---|
| File Type | Plain text flat table | Zipped XML spreadsheet | Binary columnar storage | Hierarchical text |
| Multiple Sheets | No (single flat table only) | Yes (multiple workbooks and sheets) | Partition-based storage | Nested arrays and objects |
| Data Types | Untyped raw text | Typed cells, formulas, formatting | Strict binary column types | Primitive types (string, number, bool) |
| Big Data Analytics | Slow (requires reading every row linearly) | Not suitable for big data | Ultra-fast (column pruning & predicate pushdown) | Moderate |
Vanliga skadeorsaker och hex-återställningsguide
⚠️ Columns shift to the right or row counts do not match.
Grundorsak: A text field containing an unescaped comma without surrounding quotation marks.
Återställning: RFC 4180 requires fields containing commas to be wrapped in double quotes: "Smith, John".
⚠️ Accented characters render as strange symbols (mojibake like é instead of é) in Excel.
Grundorsak: Excel opened a UTF-8 CSV assuming the legacy Windows ANSI/CP1252 character encoding.
Återställning: Prepend the 3-byte UTF-8 Byte Order Mark (0xEF 0xBB 0xBF) to the beginning of the file.
Säkerhetsanalys och attackvektorer för tolkar
CSV files open directly in spreadsheet software like Excel and Google Sheets, exposing users to Formula Injection (CSV Injection) attacks.
Kända attackvektorer
- Formula Injection: Cells starting with '=', '+', '-', or '@' executing spreadsheet macros or DDE commands (e.g. '=cmd|' /C calc'!A0').
- Data exfiltration via HYPERLINK() formulas sending sensitive cell data to remote attacker servers upon click.
Rekommenderade skyddsåtgärder: When exporting user data to CSV, prepend a single quote (') or tab to any cell starting with '=', '+', '-', or '@' to force plain text rendering in Excel.
Historiskt ursprung och milstolpar
Viktiga fördelar
- Maximum simplicity: readable in any text editor and importable into every database and spreadsheet.
- Extremely fast line-by-line streaming without building a full in-memory DOM.
- Minimal overhead: no verbose tag syntax or schema definitions.
Tekniska begränsningar
- No standard data types: numbers, dates, booleans, and text are all stored as raw strings.
- No support for multiple sheets, cell formatting, formulas, or metadata.
- Delimiter conflicts (commas inside text, decimal commas in European locales) cause frequent parsing bugs.
Intressant teknisk kuriosa
- In many European countries where commas are used as decimal points, semicolons (;) are used instead of commas as CSV separators.
- Microsoft Excel historically required a UTF-8 BOM (0xEF 0xBB 0xBF) to correctly display non-ASCII accented characters.
Vanliga tekniska frågor
What is RFC 4180?
RFC 4180 is the official IETF standard for CSV. It mandates that fields containing commas, line breaks, or double quotes must be enclosed in double quotes, and internal quotes must be escaped by doubling them ("").
Why do CSV files open with corrupted characters in Excel?
Older versions of Microsoft Excel default to the local Windows code page (like Windows-1252) rather than UTF-8 when opening CSV files directly. Adding a UTF-8 BOM (Byte Order Mark) at the start of the file forces Excel to decode UTF-8 correctly.
Relaterade konverteringspar för CSV
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