C# Code Snippets

A bunch of random C# code snippets that might help.

Extensions

Date Extensions

IsWeekend

Check if DayOfWeek is Saturday or Sunday. (Note: This does not apply to all countries and cultures. I found it useful for Brazil.)

ToFirstDayOfMonth

Returns the first day of the month for the specified DateOnly/DateTime/DateTimeOffset.

ToLastDayOfMonth

Returns the last day of the month for the specified DateOnly/DateTime/DateTimeOffset.

GetIso8601WeekNumber

Returns the week of the year, according to ISO-8601, for the specified DateTime.

Stream Extensions

ReadLinesAsync

Returns an iterator to read a stream line by line

String Extensions

Reverse

Reverses a given string. e.g. ABCD => DCBA

ToSnakeCase

Convert string to snake_case format. e.g. CodeSnippets => code_snippets

Helpers

Validation Helpers

IsValidCnpj

Check if the given string is a valid CNPJ.

IsValidCpf

Check if the given string is a valid CPF.