Variable Naming Rules in C#

TL ; DR:

• In C#, we use the camelCase convention to name our variables. It implies separating different words with capital letters, like this:

  string companyName = "Apple";
  
  int foundingYear = 1976;
  
  bool isUnicorn = true;
  
  int numberOfEmployees = 137000;
  

  
  

Full lesson:

Variable names must consist ONLY of letters, numbers and underscores and they must start with a letter or underscore.

Bad variable names:

int 18spam;
string x.15;
bool #name;

If you try to create a variable with any of these names, C# will throw an error.

Naming conventions: camelCase and snake_case

Sometimes a variable name might consist of multiple words, for example if you want to store the first name of a person. You might be tempted to separate those names by whitespaces, like this:

string first name = "Kate";

This code will also throw an error.

When you name your variables, you want to use one of these two conventions:

snake_case = separate different words with an underscore (_), like this:

string first_name = "Jane";
string last_name = "Doe";

camelCase = separate different words with capital letters, like this:

string firstName = "Jane";
string lastName = "Doe";

It's important to be consistent with the casing technique you use. Do not combine both of them in the same code, like this:

string first_name = "Jane";
string lastName = "Doe";

Case sensitive:

Variable names are case sensitive:

string name = "Kate";
string Name = "Andy";
string NAME = "George";

Console.WriteLine(name + " " + Name + " " + NAME); // Output: Kate Andy George

Although C# allows us to do this, it's always confusing and a bad coding practice to differentiate variable names just by case!

Mnemonic Variable Names:

Since we programmers are given a choice in how we choose our variable names, there is a bit of "best practice".

Sometimes we want them short like x and y, but sometimes we want them descriptive, especially if they are important.

Here is a great example:

int a = 25;
int b = 13;
int c = a * b;
Console.WriteLine(c);

compared to:

int hours = 25;
int rate = 13;
int pay = hours * rate;
Console.WriteLine(pay);

C# understands and is happy with both of these pieces of code. But it's clearly which version makes your reader happier.