day 6：循环 | 易学教程

一、while循环

while True：死循环，只能使用break

break：退出当前循环

continue：继续下一轮循环

pass 在循环体或者函数体空时防止报错

import random #引入随机数

luck_num = random.randint(10,99)
luck_num_g = luck_num % 10
luck_num_s = luck_num //10

while True:
    buy_num = int(input("请输入一个两位数："))
    if buy_num == luck_num:
        print("一等奖")
        break
    elif buy_num % 10 == luck_num_s and buy_num //10 == luck_num_g:
        print("二等奖")
        break
    else:
        print("遗憾,没中奖")

二、使用while打印乘法表

正三角

i = 1
while i < 10:
    j = 1
    while j <= i:
        print(j,"x",i,"=",i*j,end=" ")
        j += 1
    print()
    i += 1

倒三角

i = 9
while i > 0:
    j = 1
    while j <= i:
        print(j,"*",i,"=",i*j,end=" ")
        j += 1
    print()
    i -= 1

向左三角

while i < 10:
    count = 0
    while count<k:
        print(end="        ")
        count+=1
    k-=1
    j = 1
    while j <= i:
        print("%s*%s=%s"%(j,i,i*j),end="\t")
        j += 1
    print()
    i += 1

向左倒三角

i = 9


while i >0:
    k = 9
    while k > i:
        print(end="        ")
        k -= 1
    j = 1
    while j <= i:
        print("%s*%s=%s"%(j,i,i*j),end="\t")
        j += 1
    print()
    i -= 1

三、使用for循环

常在遍历时候使用，

在字典中取出键值，但可以用var.values()获得键值,用var.items()得到它本身

var = "今年过年不收礼啊，"
for val in var:
    print(val)
#for循环嵌套
var = ["python","hello","java","c"]
for val in var:
    print(val)
    for res in val:
        print(res)

var = {"a":1,"b":2,"c":3}
for val in var.items():
    print(val)

#在二级列表的使用中，可以使用abc这样的获得相应值，要求长度相同
var = [[1,2,3],[4,5,6],[7,8,9]]
for a,b,c in var:
    print(a,b,c)

range(a,b) a为起始，b为最大值-1，(如果没有a那么就是从0开始通过for循环打印乘法表

for i in range(1,10):
    for j in range(1,i+1):
        print("%sx%s=%s"%(j,i,i*j),end="\t")
    print()



for i in range(1, 10):
    for j in range(i, 10):
        print("%sx%s=%s" % (i, j, i * j), end="\t")
    print()



for i in range(1, 10):
    for k in range(1, 10 - i):
        print(end="        ")
    for j in range(1, i + 1):
        print("%sx%s=%s" % (j, i, i * j), end="\t")
    print()

来源：CSDN

作者：JJ1M8

链接：https://blog.csdn.net/JJ1M8/article/details/104331551

标签

for循环

num

var