一、while循环
dead loop(死循环): | while True |
continue | 跳出本次循环,接着还执行后面的循环 |
break | 完全终止循环 |
#!/usr/bin/python
#Author:linyaohng
count = 0
while count <=100:
print("loop:",count)
count +=1
print(".......End............")
[root@test01 /home]# python while1.py
loop: 0
loop: 1
....
loop: 100
.......End............
打印1-100之间的偶数
[root@test01 /home]# cat while2.py
#!/usr/bin/python
#Author:linyaohng
count = 0
while count <=100:
if count %2 == 0:
print("loop:",count)
count +=1
print(".......End............")
[root@test01 /home]# python while2.py
loop: 0
loop: 2
loop: 4
.......
.......End............
打印1-100、单不打印50且60-80取平方数、if 条件
pass #如果条件成立则不执行 pass 新知识点
pass #如果条件成立则不执行 pass 新知识点
[root@test01 /home]# cat while3.py
#!/usr/bin/python
#Author:linyaohng
count = 0
while count <=100:
if count == 50:
pass
elif count >=60 and count <=80:
print("loop",count*count)
else:
print("loop",count)
count +=1
print(".......End............")
[root@test01 /home]# python while3.py
loop 0
loop 1
loop 2
..............
.......End...........
二、dead loop ------- while True:
[root@test01 /home]# cat while4.py
#!/usr/bin/python
#Author:linyaohng
count = 0
while True:
print("loop:",count)
count +=1
三、break
#!/usr/bin/python
#Author:linyaohng
count = 0
while count <=100:
print("loop:",count)
if count == 5:
break
count +=1
print("........Een.........")
[root@test01 /home]# python while5.py
loop: 0
loop: 1
loop: 2
loop: 3
loop: 4
loop: 5
........Een.........
不打印0
[root@test01 /home]# cat while8.py
#!/usr/bin/python
#Author:linyaohng
count = 0
while count <=100:
count +=1
print("loop:",count)
if count == 5:
break
print("........Een.........")
[root@test01 /home]# python while8.py
loop: 1
loop: 2
loop: 3
loop: 4
loop: 5
........Een.........
不打印0和5
[root@test01 /home]# cat while9.py
#!/usr/bin/python
#Author:linyaohng
count = 0
while count <=100:
count +=1
if count == 5:
break
print("loop:",count)
print("........Een.........")
[root@test01 /home]# python while9.py
loop: 1
loop: 2
loop: 3
loop: 4
........Een.........
四、continue
[root@test01 /home]# cat while6.py
#!/usr/bin/python
#Author:linyaohng
count = 0
while count <=100:
print("loop:",count)
if count == 5: #这里到5以后不会执行count +=1,所以一直是5,进入死循环
continue
count +=1
print("........Een.........")
[root@test01 /home]# python while6.py
loop: 0
loop: 1
loop: 2
loop: 3
loop: 4
loop: 5
loop: 5
loop: 5
.......
....
#无限循环5,死循环
把count +=1和打印调整一下位置
此时就会跳过5不打印、直到循环结束
此时就会跳过5不打印、直到循环结束
[root@test01 /home]# cat while7.py
#!/usr/bin/python
#Author:linyaohng
count = 0
while count <=100:
count +=1
if count == 5:
continue
print("loop:",count)
print("........Een.........")
[root@test01 /home]# python while7.py
loop: 1
loop: 2
loop: 3
loop: 4
loop: 6
loop: 7
loop: 8
....
loop: 101
........Een.........
选择性打印
[root@test01 /home]# cat while10.py
#!/usr/bin/python
#Author:linyaohng
count = 0
while count <=100:
count +=1
if count > 5 and count < 95:
continue
print("loop:",count)
print("........Een.........")
[root@test01 /home]# python while10.py
loop: 1
loop: 2
loop: 3
loop: 4
loop: 5
loop: 95
loop: 96
loop: 97
loop: 98
loop: 99
loop: 100
loop: 101
........Een........
总结:当条件和要执行的命令位置不同时、执行结果不同