Dart Syntax: Identifiers

Identifiers can include letters (both uppercase and lowercase), digits, and underscores.
They must start with a letter (a-z or A-Z), an underscore (_), or a dollar sign ($).
Dart is case-sensitive, so myVariable and MyVariable are considered different identifiers.
Identifiers cannot be reserved words or keywords used by Dart.
Camel Case Convention:
- Dart conventionally uses camel case for identifiers. In camel case, the first word starts with a lowercase letter, and the subsequent words are capitalized. This is commonly used for variables and functions.
```
  dartCopy codevar myVariable;
  void calculateTotalAmount() {
    // code
  }
```
Pascal Case Convention:
- For class names, Dart often follows the Pascal case convention. In Pascal case, the first letter of each word is capitalized.
```
  dartCopy codeclass Person {
    // class definition
  }
```
Underscores:
- Dart allows identifiers to start with an underscore. This is often used to indicate that the identifier is private to its library.
```
  dartCopy codevar _secretVariable;
```
Dollar Sign:
- Dart allows the use of the dollar sign in identifiers. This is often used in string interpolation and can be part of variable names.
```
  dartCopy codevar $price = 10;
  print($price); // 10
```
Reserved Words:
- Certain words are reserved by Dart and cannot be used as identifiers. For example, int, double, if, else, and so on.
```
  dartCopy code// This is not allowed
  var int = 5;
```