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CSVFile

This library is a series of unit tested, thoroughly commented CSV parsing functions which I have developed off and on since 2006. Extremely small and easy to implement; includes unit tests for the majority of odd CSV edge cases. Library supports different delimiters, qualifiers, and embedded newlines. Can read and write from data tables.

Why use CSVFile?

A few reasons:

  • Compatible with DotNet Framework / C# 2.0 and later. Makes it easy to integrate this library into extremely old legacy projects.
  • Between 16-32 kilobytes in size, depending on framework.
  • No dependencies.
  • Handles all the horrible edge cases from poorly written CSV generating software: custom delimiters, embedded newlines, and doubled-up text qualifiers.
  • Reads via streams, optionally using asynchronous I/O. You can parse CSV files larger than you can hold in memory without thrashing.
  • Ability to pipe data tables directly into SQL Server using Table Parameter Inserts
  • Fastest with direct string parsing or async I/O, but good enough performance when reading from MemoryStreams

CSV edge cases

This library was designed to handle edge cases I experienced when working with partner files.

Case Example
CSV files larger than can fit into memory streamed off disk 10TB files
Pipe delimited files field1|field2
Hand written CSV with spaces after deliminters "field1", "field2", "field3"
Embedded newlines within a text qualifier "field1\r\nanother line","field2"
Text qualifiers as regular characters within a field "field1",field2 "field2" field2,"field3"
Doubled up text qualifiers within a qualified field "field1","field2 ""field2"" field2","field3"
Different line separators CR, LF, something else
Different text encoding UTF-8, UTF-16, ASCII
SEP= lines for European CSV files sep=;\\r\\n

Tutorial

Want to get started? Here are a few walkthroughs.

Custom CSV Settings

Do you have files that use the pipe symbol as a delimiter, or does your application need double quotes around all fields? No problem!

var settings = new CSVSettings()
{
    FieldDelimiter = '|',
    TextQualifier = '\'',
    ForceQualifiers = true
};
s = array.ToCSVString(settings);

Streaming asynchronous CSV

The latest asynchronous I/O frameworks allow you to stream CSV data off disk without blocking. Here's how to use the asynchronous I/O features of Dot Net 5.0:

using (var cr = CSVReader.FromFile(filename, settings)) {
    await foreach (string[] line in cr) {
        // Do whatever you want with this one line - the buffer will
        // only hold a small amount of memory at once, so you can 
        // iterate at your own pace!
    }
}

Streaming CSV without async

Don't worry if your project isn't yet able to use asynchronous foreach loops. You can still use the existing reader logic:

using (CSVReader cr = new CSVReader(sr, settings)) {
    foreach (string[] line in cr) {
        // Process this one line
    }
}

Serialize and Deserialize

You can serialize and deserialize between List and CSV arrays. Serialization supports all basic value types, and it can even optionally support storing null values in CSV cells.

var list = new List<MyClass>();

// Serialize an array of objects to a CSV string
string csv = CSV.Serialize<MyClass>(list);

// Deserialize a CSV back into an array of objects
foreach (var myObject in CSV.Deserialize<MyClass>(csv)) {
    // Use the objects
}

Data Table Support (for older DotNet frameworks)

For those of you who work in older frameworks that still use DataTables, this feature is still available:

// This code assumes the file is on disk, and the first row of the file
// has the names of the columns on it
DataTable dt = CSV.LoadDataTable(myfilename);

// Save a datatable to a file
dt.SaveAsCSV(myfilename, true);

Hand Roll Your Own

The class CSV contains a lot of useful functions for hand rolling your own CSV related code. You can use any of the functions in the CSV class directly.

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A lightweight, high performance, zero dependency, streaming CSV reading library for CSharp.

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