How to use python's while

Python While loop statement

The while statement in Python programming is used to execute the program in a loop, that is, under certain conditions, execute a certain program in a loop , to handle the same tasks that need to be processed repeatedly.

The basic form is: (Recommended learning: Python video tutorial)

while 判断条件：
    执行语句……

The execution statement can be a single statement or statement block. The judgment condition can be any expression, and any non-zero or non-null value is true.

When the judgment condition is false, the loop ends.

There are two other important commands in the while statement: continue, break is used to skip the loop, continue is used to skip the loop, break is used to exit the loop, in addition" The judgment condition "can also be a constant value, indicating that the loop must be established. The specific usage is as follows:

# continue 和 break 用法
 i = 1while i < 10:   
    i += 1
    if i%2 > 0:     # 非双数时跳过输出
        continue
    print i         # 输出双数2、4、6、8、10
 i = 1while 1:            # 循环条件为1必定成立
    print i         # 输出1~10
    i += 1
    if i > 10:     # 当i大于10时跳出循环
        break

Loop uses the else statement

In python, while...else is in the loop When the condition is false, the else statement block is executed:

#!/usr/bin/python
 
count = 0
while count < 5:
   print count, " is  less than 5"
   count = count + 1
else:
   print count, " is not less than 5"

The output result of the above example is:

0 is less than 5
1 is less than 5
2 is less than 5
3 is less than 5
4 is less than 5
5 is not less than 5

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