{"id":1280,"date":"2023-03-30T10:42:27","date_gmt":"2023-03-30T03:42:27","guid":{"rendered":"https:\/\/csharptutorial.net\/?page_id=1280"},"modified":"2023-03-30T10:42:28","modified_gmt":"2023-03-30T03:42:28","slug":"csharp-write-csv-files","status":"publish","type":"page","link":"https:\/\/www.csharptutorial.net\/csharp-file\/csharp-write-csv-files\/","title":{"rendered":"C# Write CSV files"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn how to use the CsvHelper<\/code> library to write data into a CSV<\/code> file from a C# program.<\/p>\n\n\n\n

This tutorial assumes that you have a quick overview of the CsvHelper<\/code> library and already install it in your project. If this is not the case, you can follow the reading from a CSV<\/code> file tutorial first.<\/p>\n\n\n\n

Writing data into a CSV file<\/h2>\n\n\n\n

The following example demonstrates how to use the CsvHelper<\/code> library to write data into a CSV<\/code> file:<\/p>\n\n\n

using<\/span> CsvHelper;\nusing<\/span> CsvHelper.Configuration.Attributes;\nusing<\/span> System.Globalization;\n\n\nclass<\/span> Employee<\/span>\n{\n    [Name(\"First Name\"<\/span>)<\/span>]\n    public<\/span> string<\/span>? FirstName { get<\/span>; set<\/span>; }\n\n    [Name(\"Last Name\"<\/span>)<\/span>]\n    public<\/span> string<\/span>? LastName { get<\/span>; set<\/span>; }\n\n    [Name(\"Joined Date\"<\/span>)<\/span>]\n    public<\/span> DateOnly? JoinedDate { get<\/span>; set<\/span>; }\n\n    [Name(\"Salary\"<\/span>)<\/span>]\n    public<\/span> decimal<\/span>? Salary { get<\/span>; set<\/span>; }\n\n    [Name(\"Active\"<\/span>)<\/span>]\n    public<\/span> string<\/span>? Active { get<\/span>; set<\/span>; }\n}\n\nclass<\/span> Program<\/span>\n{\n    static<\/span> void<\/span> Main<\/span>(string<\/span>[] args<\/span>)<\/span>\n    {\n        var<\/span> employees = new<\/span> List<Employee> {\n           new<\/span> Employee {\n              FirstName = \"John\"<\/span>, LastName = \"Doe\"<\/span>, JoinedDate = new<\/span> DateOnly(2020<\/span>, 1<\/span>, 1<\/span>), Salary = 50000.00<\/span>M, Active = \"Yes\"<\/span>\n           },\n           new<\/span> Employee {\n              FirstName = \"Jane\"<\/span>, LastName = \"Doe\"<\/span>, JoinedDate = new<\/span> DateOnly(2021<\/span>, 6<\/span>, 15<\/span>), Salary = 60000.00<\/span>M, Active = \"Yes\"<\/span>\n           },\n           new<\/span> Employee {\n              FirstName = \"Bob\"<\/span>, LastName = \"Smith\"<\/span>, JoinedDate = new<\/span> DateOnly(2019<\/span>, 3<\/span>, 10<\/span>), Salary = 70000.00<\/span>M, Active = \"No\"<\/span>\n           }\n        };\n\n\n        using<\/span> var<\/span> writer = new<\/span> StreamWriter(\"output.csv\"<\/span>);\n        using<\/span> var<\/span> csv = new<\/span> CsvWriter(writer, CultureInfo.InvariantCulture);\n\n\n        csv.WriteHeader<Employee>();\n        csv.NextRecord();\n        foreach<\/span> (var<\/span> employee in<\/span> employees)\n        {\n            csv.WriteRecord(employee);\n            csv.NextRecord();\n        }\n\n    }\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
The contents of the output.csv file will look like this:<\/p>\n\n\n
First Name,Last Name,Joined Date,Salary,Active\r\nJohn,Doe,01\/01\/2020,50000.00,Yes\r\nJane,Doe,06\/15\/2021,60000.00,Yes\r\nBob,Smith,03\/10\/2019,70000.00,No\r<\/code><\/span>Code language:<\/span> plaintext<\/span> (<\/span>plaintext<\/span>)<\/span><\/small><\/pre>\n\n\n
How it works.<\/p>\n\n\n\n
First, define the Employee<\/code> class that has properties for first name, last name, joined date, salary, and active status:<\/p>\n\n\n
class<\/span> Employee<\/span>\n{\n    [Name(\"First Name\"<\/span>)<\/span>]\n    public<\/span> string<\/span>? FirstName { get<\/span>; set<\/span>; }\n\n    [Name(\"Last Name\"<\/span>)<\/span>]\n    public<\/span> string<\/span>? LastName { get<\/span>; set<\/span>; }\n\n    [Name(\"Joined Date\"<\/span>)<\/span>]\n    public<\/span> DateOnly? JoinedDate { get<\/span>; set<\/span>; }\n\n    [Name(\"Salary\"<\/span>)<\/span>]\n    public<\/span> decimal<\/span>? Salary { get<\/span>; set<\/span>; }\n\n    [Name(\"Active\"<\/span>)<\/span>]\n    public<\/span> string<\/span>? Active { get<\/span>; set<\/span>; }\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Notice that we mark these properties with the Name<\/code> attribute, which specifies the column names of the output CSV<\/code> files.<\/p>\n\n\n\n
Next, create a List<\/code> of Employee<\/code> objects and initialize it with some sample data in the Main()<\/code> method of the Program<\/code> class:<\/p>\n\n\n
var<\/span> employees = new<\/span> List<Employee> {\n   new<\/span> Employee {\n      FirstName = \"John\"<\/span>, LastName = \"Doe\"<\/span>, JoinedDate = new<\/span> DateOnly(2020<\/span>, 1<\/span>, 1<\/span>), Salary = 50000.00<\/span>M, Active = \"Yes\"<\/span>\n   },\n   new<\/span> Employee {\n      FirstName = \"Jane\"<\/span>, LastName = \"Doe\"<\/span>, JoinedDate = new<\/span> DateOnly(2021<\/span>, 6<\/span>, 15<\/span>), Salary = 60000.00<\/span>M, Active = \"Yes\"<\/span>\n   },\n   new<\/span> Employee {\n      FirstName = \"Bob\"<\/span>, LastName = \"Smith\"<\/span>, JoinedDate = new<\/span> DateOnly(2019<\/span>, 3<\/span>, 10<\/span>), Salary = 70000.00<\/span>M, Active = \"No\"<\/span>\n   }\n};<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Then, create a StreamWriter<\/code> object to write to a CSV<\/code><\/code> file named “output.csv<\/code>“. Also, create a CsvWriter<\/code> object, which writes the data to the CSV<\/code><\/code> file:<\/p>\n\n\n
using<\/span> var<\/span> writer = new<\/span> StreamWriter(\"output.csv\"<\/span>);\nusing<\/span> var<\/span> csv = new<\/span> CsvWriter(writer, CultureInfo.InvariantCulture);<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
We configure the CsvWriter<\/code> object with the InvariantCulture<\/code>, which formats the output consistently regardless of the user’s cultural settings.<\/p>\n\n\n\n
After that, write the header row to the CSV<\/code> file by calling the WriteHeader()<\/code> method of the CsvWriter<\/code> object. <\/p>\n\n\n
csv.WriteHeader<Employee>();<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Then, call the NextRecord()<\/code> method to move to the next row:<\/p>\n\n\n
csv.NextRecord();<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Finally, iterate through each Employee<\/code> object in the list, calls the WriteRecord<\/code> method of the CsvWriter<\/code> object to write the employee data to the current row, and call the NextRecord<\/code> method to move to the next row: <\/p>\n\n\n
foreach<\/span> (var<\/span> employee in<\/span> employees)\n{\n    csv.WriteRecord(employee);\n    csv.NextRecord();\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Summary<\/h2>\n\n\n\n
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  • Use the CsvHelper<\/code> library to write data into a CSV<\/code> file.<\/li>\n<\/ul>\n
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