Flutter dart控制流程

选择结构

（1）if-else

dart 复制代码

  int i = 10;
  if (i > 0) {
    
    print("Yes");
  }else{

    print("No");
  }

dart 复制代码

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

（2）switch-case

dart 复制代码

//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;
  }

dart 复制代码

//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

dart 复制代码

  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)

dart 复制代码

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

（2）while

dart 复制代码

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

（3）do-while

dart 复制代码

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

注释

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