Variables and Datatypes in Dart

In Dart, variables are used to store data values. Each variable has a specific data type, which determines the kind of values it can hold. Dart is a statically typed language, which means that variables must be declared with their data types before they can be used.

Variable Declaration

In Dart, variables can be declared using the var keyword followed by the variable name and an optional initial value. Here's an example:

var name = 'John';

In the above example, the variable name is declared using the var keyword. The variable name is name and the initial value is 'John'. The variable name is of type String because the initial value is a string.

The var keyword is optional. You can also declare variables using the data type of the initial value. Here's an example:

String name = 'John';

In the above example, the variable name is declared using the String data type. The variable name is name and the initial value is 'John'. The variable name is of type String because the initial value is a string.

Variable Assignment

In Dart, variables can be assigned new values using the assignment operator =. Here's an example:

var name = 'John';
name = 'Jane';

Output

Jane

In the above example, the variable name is assigned the value 'John' and then the value 'Jane'.

Datatypes in Dart

In Dart, variables can be declared using the following data types:

• int - for integer values
• double - for floating-point values
• num - for numeric values
• String - for string values
• bool - for boolean values
• List - for list values
• Map - for map values
• dynamic - for dynamic values

We will discuss more about List and Map in the Dart collections chapter.

int

In Dart, the int data type is used to represent integer values. Here's an example:

int age = 20;

In the above example, the variable age is declared using the int data type. The variable name is age and the initial value is 20. The variable age is of type int because the initial value is an integer.

double

In Dart, the double data type is used to represent floating-point values. Here's an example:

double pi = 3.14;

In the above example, the variable pi is declared using the double data type. The variable name is pi and the initial value is 3.14. The variable pi is of type double because the initial value is a floating-point value.

num

In Dart, the num data type is used to represent numeric values. Here's an example:

num pi = 3.14;

In the above example, the variable pi is declared using the num data type. The variable name is pi and the initial value is 3.14. The variable pi is of type num because the initial value is a numeric value.

String

In Dart, the String data type is used to represent string values. Here's an example:

String name = 'John';

In the above example, the variable name is declared using the String data type. The variable name is name and the initial value is 'John'. The variable name is of type String because the initial value is a string value.

bool

In Dart, the bool data type is used to represent boolean values. Here's an example:

bool isMarried = false;

In the above example, the variable isMarried is declared using the bool data type. The variable name is isMarried and the initial value is false. The variable isMarried is of type bool because the initial value is a boolean value.

dynamic

In Dart, the dynamic data type is used to represent dynamic values. Here's an example:

dynamic age = 20;

In the above example, the variable age is declared using the dynamic data type. The variable name is age and the initial value is 20. The variable age is of type dynamic because the initial value is a dynamic value.

Type Inference

In Dart, the var keyword can be used to declare variables without specifying their data types. Here's an example:

var name = 'John';

In the above example, the variable name is declared using the var keyword. The variable name is name and the initial value is 'John'. The variable name is of type String because the initial value is a string.

In Dart, the var keyword can also be used to declare variables without specifying their data types. Here's an example:

var age = 20;

In the above example, the variable age is declared using the var keyword. The variable name is age and the initial value is 20. The variable age is of type int because the initial value is an integer.

Conclusion

In this chapter, we learned about variables and data types in Dart. In the next chapter, we will learn about keywords const and final in Dart.