Python 中断语句详细信息

Question

任何人都可以提供有关此问题的详细信息吗？

for i in range(1,10):
      if i == 5:
           break
      print("number is ", i)


Output:
number is 1
number is 2
number is 3
number is 4

我的问题是：为什么没有来5个？？我在这里告诉我 == 5 这意味着当 i 值为 5 时它应该中断并给出结果 5 。

now,  if i > 5:
         break
    print(i)
Output: 
     number is 1
     number is 2
     number is 3
     number is 4
     number is 5

这里 5 > 5 不是真的。那它呢？？

最后一件事 if 结构

for i in range(1,10):
print(i)
if i < 5:
    break

 Output: only 1

问题：结果至少应该是 1 到 4 。但不是为什么？

感谢大家。希望您能理解并详细说明我的问题。

Answer 1

在第 i = 5 次迭代中，您通过了 if 测试的条件并执行语句的 then 块，其中包含 break。 break 语句使您退出循环。打印语句是循环体的一部分，在 i=5.

的迭代中永远不会到达

Answer 2

它没有打印 5 的原因是因为你在它到达 print("number is ", i) 之前中断了循环。

for i in range(1,10):
      if i == 5: #when i is 5 this will be true
           break #break the loop exits the loop
      #----------------------This is not run when i==5 because the loop already ended
      print("number is ", i)

如果你想打印 5

for i in range(1,10):

     print("number is ", i) #put this in front
     if i == 5: #when i is 5 this will be true
           break #break the loop exits the loop

附带说明：range(1,10) 实际上是 [1,2,3,4,5,6,7,8,9]，不包括十，因为 python 跳过了最后一个

对OP的评论：

for i in range(1,10):

     if i > 5: #when i is 5 this will be false, so the loop doesn't break
           break #break the loop when i > 5 (ie. 6) so now the print() isn't reached and will not print 6

     print("number is ", i) #since the loop didn't break when i is 5, it printed i

你另外两个新例子：

for i in range(1,10):
    if i > 5:
         break #exits here skips the print since it's after this
    print(i) #the print statement is here so when i > 5 this is not reached
#on the other hand:
for i in range(1,10):
    print(i) #the print statement is in front of the break statement so now it will print 6 too since the loop hasn't break yet
    if i > 5:
         break #exits here after the print()
#output also includes 6

最后一件事 if 结构

for i in range(1,10):
    print(i) #only 1 got printed since the loop break before it get to 2
    if i < 5: #when i < 5 so it breaks in the first loop when i is 1
        break #exits the loop

你可能想看看 this 看看是否有帮助

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