python **while*语句的一般i形式*
* for 变量 in 列表:
while 判断条件 :
语句
循环体
else:
不符合循环条件的语句*
while 和 for 的区别
while在不确定循环次数的情况下用: 小明写作业
for 在确定次数下用: 三角形, 99乘法表
break 结束循环 continue 结束本次循环
pass 占个位置 充当一条语句 本身不会执行任何操作
while for 练习
1.打印直角三角形
num = 1
while num < 5:
n = 1
whlie n< =num:
print("*",end = "")# end="" 不换行
n += 1
num += 1
print()
for num in range(1,5)
for n in range(1,num)
print(" * ",end= "")
print()
2.99乘法表
num = 1
while num < 10:
n = 1
while n <= num:
print(n,"*",num,"=",(n*num),end="\t")
n += 1
print()
num += 1
for num in range(1,10)
for n in range(1.num+1)
print(n,"*",num,"=",(n*num),end="\t")
print()
3.菱形(标记,以后学多了,回来改)
a= int(input("请输入数值:"))
for num in range(1,a):
if a %2 == 0 :
if num <= a//2:
for n in range(a//2-num):
print(" ",end="")
for n in range(num):
print("* ",end="")
else:
if num <= a//2:
for n in range(a//2+1-num):
print(" ",end="")
for n in range(num):
print("* ",end="")
if num > a//2:
for n in range(num-(a//2)):
print(" ",end="")
for n in range(a-num):
print("* ", end="")
print()