How to convert CamelCase to snake_case in C#?

Question:

I would like to know how I can convert a string with CamelCase to snake_case in C#.

For example:

 EuAmoCsharp => eu_amo_csharp
 SnakeCase   => snake_case

Answer:

It would be something like this:

string stringSnake = string.Concat(
                         stringCamel.Select((x, i) => i > 0 && char.IsUpper(x) ? "_" + x.ToString().ToLower() : x.ToString().ToLower())
                     ); 

I made a Fiddle for you .

Explaining:

string is an enumeration of char in C#. So I can use:

stringCamel.Select()

One way to use Select is to specify two variables in the predicate, where x the current character of the iteration and i the index of that iteration.

The conditional is simpler to understand:

i > 0 && char.IsUpper(x) ? "_" + x.ToString().ToLower() : x.ToString().ToLower()

I check if i is greater than zero and if the current character is uppercase, because I don't want to write _ before the first character.

If the character is uppercase, I write _ and the character in lowercase. Otherwise I just write the character.

I need to keep ToLower() on both results because of the first character.