Flutter dart控制流程

选择结构

（1）if-else

  int i = 10;if (i > 0) {print("Yes");}else{print("No");}

  int i = -50;if (i > 10) {print("A");} else if (i < -10) {print("B");} else {print("c");}

（2）switch-case

//与java用法 没什么区别int i = 40;switch (i) {case 10:print("10");break;case 20:case 30:print("大于20");break;default:print("default");break;}

//continue 用法var i = 10;switch (i) {case 10:print("10");continue abc;case 20:case 30:print("大于20");break;abc:default:print("default");break;}I/flutter ( 3700): 10
I/flutter ( 3700): default

循环结构
（1）for

  int sum = 0;for (int i = 0; i <= 100; i++) {sum = sum + i;}print(sum);

比较特别，类似java for(string str:list)

  List ll = [1,2,3,4,5,6,7,8,9];for(var  i in ll){print(i);}

（2）while

  var sum = 0;var i = 1;while (i <= 100) {sum = sum + i;i++;}print(sum);

（3）do-while

  var sum = 0;var i = 1;do{sum = sum + i;i++;}while(i<=100);print(sum);

注释

1. 单行注释 //
2. 多行注释 /* * /
3. 文档注释 ///