What is Variables?
1. Variables are containers used to store value in the program.
2. Variables can be of different types, such as integers, floating-point numbers, strings, Booleans, and more.
3. To declare a variable in Dart, you use the var keyword followed by the variable name and an optional value
4. Syntax – var variableName = value;
5. Syntax – type variableName = value; //here type is datatype
var name = 'Nandan';
var age = 23;
var isMarried = false;
You can also specify the type of a variable explicitly using the Type syntax:
String name = 'Nandan';
int age = 23;
bool isMarried = false;
Some Rules In Variables
1. Variable names are case sensitive, i.e., a and A are different.
2. A variable name can consist of letters and alphabets.
3. A variable name cannot start with number.
4. Keywords are not allowed to use as a variable name.
5. Blank spaces are not allowed in a variable name.
6. Special characters are not allowed except for the underscore (_) and the dollar ($) sign.
Types Of Variables
1. String: For storing text value. E.g. “Nandan” [Must be in quotes]
2. int: For storing integer value. E.g. 7, -10, 1234 [Decimal is not included]
3. double: For storing floating point value. E.g. 10.0, -10.2, 85.698 [Decimal is included]
4. num: For storing any types of number. E.g. 10, 20.2, -20 [both int and double]
5. bool: For storing true or false value. E.g. true, false [Only stores true or false values]
6. var: For storing any value. E.g. ‘Small’, 12, ‘z’, true, false
Using constant in dart
Constant is the type of variable whose value never changes.
void main() {
String name = "Nandan";
String address = "Karnataka";
int age = 23;
bool isDegreeFinished = true;
var info = "Curious Developers Community";
print("Name is $name");
print("Address is $address");
print("Age is $age");
print("Degree Status is $isDegreeFinished");
print("info is $info");
//constant in dart
const String constant_info = "Nochange";
print("No Change in information $constant_info");
}
/*
Name is Nandan
Address is Karnataka
Age is 23
Degree Status is true
info is Curious Developers Community
No Change in information Nochange
*/Naming Conventions
In Dart the variable name should start with lower-case, and every second word’s first letter will be upper-case like num1, fullName, isMarried, etc. Technically, this naming convention is called lowerCamelCase.
// Incorrect Way
var fullname = "Nandan";
// Correct Way
var fullName = "Nandan";
const pi = 3.14;Project – 2 Details Generator
In this project we will generate a simple details of the person by using variables
void main()
{
String name = "Nandan";
String email = "info@curiousdevelopers.in";
int rollNum = 7;
int age = 23;
print("My name is $name, I'm $age years old, My roll number is $rollNum and My email id is $email");
}
/*
My name is Nandan, I'm 23 years old, My roll number is 7 and My email id is info@curiousdevelopers.in
*/