循环语句：while

1. while语句结构：while+条件

• 示例1：

  while True:
      print("人生苦短，我用Python。")
  

  运行得到的结果是循环打印“人生苦短，我用python。”
  

• 示例2：

  while 1>0 and 2>1:
      print("人生苦短，我用Python。")
  

  运行得到的结果也是循环打印“人生苦短，我用python。”

• 示例3
  通过循环，让count每次都+1

  count = 1
  while True:
      print(count)
      count = count + 1
  

  运行得到的结果是，从1开始每次循环+1
  

• 示例4
  通过循环，打印从1到10

  count = 1
  while count <= 10:
      print(count)
      count = count + 1
  print("结束")
  

  运行结果
  

• 示例5
  通过循环，打印从1、2、3、4、5、6、8、9、10

  # 我的方法
  count = 1
  while count <= 10:
      print(count)
      count = count + 1
      if count == 7:
          count = count +1
  print("结束")
  

  运行结果
  

  其他方法同样可以实现：

  # 其他同学的方法
  count = 1
  while count <= 6:
      print(count)
      count = count + 1
  count = 8
  while count <= 10:
      print(count)
      count = count + 1
      
  # 老师的方法1
  count = 1
  while count <= 10:
      if count != 7:
          print(count)
      count = count + 1
  print("结束")
  
  # 老师的方法2
  count = 1
  while count <= 10:
      if count == 7:
          pass
      else:
          print(count)
      count = count + 1
  print("结束")
  

2. 关键字：break

break，跳出当前循环

• 示例1

  count = 1
  while count <= 10:
      if count == 7:
          break
      print(count)
      count = count + 1
  print("结束")
  

  运行结果
  

• 示例2：通过break实现，打印1~10

  count = 1
  while True:
      print(count)
      if count == 10:
          break
      count = count + 1
  print("结束")
  

  运行结果
  

3. 关键字：continue

continue，本次循环如果遇到continue，则不再继续向下运行，回到while条件位置

• 示例：使用continue，打印1，2，3，4，5，6，8，9，10

  # 方法1
  count = 1
  while count <= 10:
      if count == 7:
          count += 1  # count += 1 ; 等效于：count = count + 1 ;
          continue
      print(count)
      count += 1
  print("结束")
  
  # 方法2
  count = 1
  while count <= 10:
      print(count)
      if count == 6:
          count += 2  
          continue
      count += 1
  print("结束")
  

  运行结果
  

4. while else

用的比较少：else在不满足while条件，或者条件为false时触发

• 示例1

  count = 1
  while count <= 10:
      print(count)
      count = count + 1
  else:
      print("正常完成")
  print("结束")
  

  运行结果
  

• 示例2

  count = 1
  while count <= 10:
      print(count)
      if count == 7:
          break
      count = count + 1
  else:
      print("正常完成")
  print("结束")
  

  运行结果
  

  因为count=7时，执行了break，跳出循环，而非while的条件不满足，因此else未执行