main 是程序的入口
// Define a function.
void printInteger(int aNumber) {
print('The number is $aNumber.'); // Print to console.
}
// This is where the app starts executing.
void main() {
var number = 42; // Declare and initialize a variable.
printInteger(number); // Call a function.
}
如何声明变量
var name = 'Bob';
Object name = 'Bob';
String name = 'Bob';
int? lineCount;
late String description;
final name = 'Bob';
final String nickname = 'Bobby';
const bar = 1000000;
const double atm = 1.01325 * bar;
late 必须在使用前初始化。
const 还可以用在值前面：
var foo = const [];
final bar = const [];
