Python入门学习之While

While 语句的结构：

while 判断条件:

       while内部的被执行语句；

eg1:

# 这是一个通过while实现的倒计时程序
import time


n = int(input("请输入倒计时秒数："));
while n:
    print(n);
    time.sleep(1);
    n = n-1;
print("time is up!")

# 带变量的while 程序
import time
n = 1;
flag = True;
while flag:
    print(n);
    
    if n == 5:
        flag = False;
    n = n+1;
    time.sleep(0.5)
print('end!');

# 带break的while 程序
import time
n = 1;
flag = True;
while flag:
    print(n);
    
    if n == 5:
        break;
    n = n+1;
    time.sleep(0.5)
print('end!');

# 带continue的while 程序
import time
n = 10;
flag = True;
while n>0:
   print("123");
   time.sleep(0.5);
   n = n-1
   continue;
   #下面的语句被continue跳过
   print("456");
    
print('end!');

# 带break和continue的while 程序


import time
n = 1;
while n<=10:
    
    
    if n == 7 :
        n = n+1;
        continue;
    if n == 0:
        break;    
    time.sleep(0.5);
    print(n);
    n = n+1;
print('end!');