Simple CSV parsing patterns
Parse CSV lines: naive Split for simple files, safe TryParse for numbers, then a small quote-aware splitter for commas inside quotes.
Simple CSV parsing patterns is a free C# Academy lesson on CoddyKit — lesson 3 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the C# Academy learning path, one of 3 lessons in the course, and your progress syncs across the web and the CoddyKit app.
CSV parsing overview
Aim: Parse small CSV reliably.
- Start with simple Split for no-quotes files
- Use TryParse for numbers
- Handle quoted fields with a tiny scanner
Naive split (no quotes)
For no-quote CSV, a simple Split works and is easy to read.
using System;
public class Program
{
public static void Main(string[] args)
{
// Simple: no quotes, commas separate fields
string line = "Apple,10,2.5";
string[] parts = line.Split(','); // naive split
Console.WriteLine("Name = " + parts[0]);
Console.WriteLine("Qty = " + parts[1]);
Console.WriteLine("Price= " + parts[2]);
}
}
Safe numeric parsing
Use Trim and TryParse with a culture (e.g., InvariantCulture) to avoid crashes on bad data.
using System;
using System.Globalization;
public class Program
{
public static void Main(string[] args)
{
string line = "Banana, 7, 1.99";
string[] p = line.Split(',');
string name = p[0].Trim();
int qty;
double price;
bool okQty = Int32.TryParse(p[1].Trim(), NumberStyles.Integer, CultureInfo.InvariantCulture, out qty);
bool okPrice = Double.TryParse(p[2].Trim(), NumberStyles.Float, CultureInfo.InvariantCulture, out price);
Console.WriteLine("Parsed: " + name + " | ok=" + (okQty && okPrice) + " -> " + qty + " x " + price);
}
}
Why naive split fails
Quoted fields may contain commas; a plain Split will break the field into pieces.
using System;
public class Program
{
public static void Main(string[] args)
{
// Name has a comma inside quotes; naive split breaks it
string line = "\"Orange, Blood\",12,3.40";
string[] parts = line.Split(','); // wrong: splits inside the quoted name
Console.WriteLine("Parts found = " + parts.Length); // 4, not 3
foreach (string s in parts) Console.WriteLine("[" + s + "]");
}
}
Quote-aware split
A small scanner toggles inQuotes and ignores commas inside quotes; it also handles doubled quotes ("").
using System;
using System.Collections.Generic;
using System.Text;
public class Program
{
// Splits a CSV line handling quotes and doubled "" inside quoted fields.
static List<string> SplitCsvLine(string line)
{
List<string> fields = new List<string>();
StringBuilder sb = new StringBuilder();
bool inQuotes = false;
for (int i = 0; i < line.Length; i++)
{
char c = line[i];
if (c == '\"')
{
if (inQuotes && i + 1 < line.Length && line[i + 1] == '\"')
{
// Escaped quote ("") inside a quoted field
sb.Append('\"');
i++; // skip next quote
}
else
{
inQuotes = !inQuotes; // toggle
}
}
else if (c == ',' && !inQuotes)
{
fields.Add(sb.ToString());
sb.Length = 0; // reset
}
else
{
sb.Append(c);
}
}
fields.Add(sb.ToString());
return fields;
}
public static void Main(string[] args)
{
string line = "\"Orange, Blood\",12,\"He said \"\"Hi!\"\"\"";
List<string> parts = SplitCsvLine(line);
Console.WriteLine("Fields = " + parts.Count);
foreach (string f in parts) Console.WriteLine("[" + f + "]");
}
}
From CSV to objects
Combine the splitter with TryParse and minimal cleanup to build typed objects safely.
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Text;
public sealed class Product
{
public string Name;
public int Quantity;
public double Price;
}
public class Program
{
static List<string> SplitCsvLine(string line)
{
List<string> fields = new List<string>();
StringBuilder sb = new StringBuilder();
bool inQuotes = false;
for (int i = 0; i < line.Length; i++)
{
char c = line[i];
if (c == '\"')
{
if (inQuotes && i + 1 < line.Length && line[i + 1] == '\"')
{ sb.Append('\"'); i++; }
else { inQuotes = !inQuotes; }
}
else if (c == ',' && !inQuotes)
{ fields.Add(sb.ToString()); sb.Length = 0; }
else
{ sb.Append(c); }
}
fields.Add(sb.ToString());
return fields;
}
static bool TryParseProduct(string line, out Product p)
{
p = null;
List<string> f = SplitCsvLine(line);
if (f.Count < 3) return false;
string name = f[0].Trim().Trim('\"');
int qty;
double price;
bool okQty = Int32.TryParse(f[1].Trim(), NumberStyles.Integer, CultureInfo.InvariantCulture, out qty);
bool okPrice = Double.TryParse(f[2].Trim(), NumberStyles.Float, CultureInfo.InvariantCulture, out price);
if (!okQty || !okPrice) return false;
p = new Product { Name = name, Quantity = qty, Price = price };
return true;
}
public static void Main(string[] args)
{
string[] lines = new string[]
{
"\"Orange, Blood\",12,3.4",
"Apple,10,2.5",
"\"He said \"\"Hi\"\"\",1,0.0"
};
List<Product> list = new List<Product>();
foreach (string line in lines)
{
Product p;
if (TryParseProduct(line, out p)) list.Add(p);
}
foreach (Product p in list)
{
Console.WriteLine(p.Name + " -> " + p.Quantity + " @ " + p.Price);
}
}
}
Quoted fields rule
Recap
Recap: Use simple Split for no-quote CSV, parse numbers with TryParse, and switch to a quote-aware scanner when fields may contain commas.
Frequently asked questions
Is the “Simple CSV parsing patterns” lesson free?
Yes — the full text of “Simple CSV parsing patterns” is free to read here on the web, and the C# Academy course includes 3 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the C# Academy course, upgrade to CoddyKit PRO.
What will I learn in “Simple CSV parsing patterns”?
Parse CSV lines: naive Split for simple files, safe TryParse for numbers, then a small quote-aware splitter for commas inside quotes. You practise C# Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start C# Academy?
No prior experience is required. C# Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 3 of 3, so you can start here or from the beginning and move at your own pace.
How long does the “Simple CSV parsing patterns” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this C# Academy lesson?
Yes. Every C# Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- System.IO (paths, streams)
- JSON with System.Text.Json (opt-ins, converters)
- Simple CSV parsing patterns