python语法学习三——循环_for i in range len(s)

while循环

#语法
while expression:
    suite_to_repeat
#代码
>>> sum=0
>>> j=1
>>> while(j<10):
	sum+=j
	j+=1
>>> sum
45
>>> j
10

for循环

#语法
for iter_var in iterable_object:
    suit_to_repeat
>>> for i in range(3,11,2):
	print(i,end='')
 
	
3579
>>> s='pyrhon'
>>> for c in s:#遍历序列迭代
	print(c,end=' ')
 
	
p y r h o n 
>>> for i in range(len(s)):#索引每一个元素迭代
	print(s[i],end=' ')
 
	
p y r h o n 

迭代过滤器

>>> x=iter(range(3,11,2))
>>> next(x)
3
>>> next(x)
5
>>> next(x)
7
>>> next(x)
9
>>> next(x)
Traceback (most recent call last):
  File "<pyshell#28>", line 1, in <module>
    next(x)
StopIteration
#判断是否为可迭代对象
>>> isinstance(range(10),Iterator)
False
>>> isinstance(iter (range(10)),Iterator)
True

猜数字游戏

#猜五次
from random import randint
x=randint(0,300)
for count in range(5):
    digit=int(input('one:'))
    if digit==x:
        print('bingo')
    else:
        if digit>x:
            print ('too large')
        else:
            print ('too small')
 

辗转相除法

x=eval(input('1='))
y=eval(input('2='))
if x<y:
    x,y=y,x
while x%y!=0:
    r=x%y
    x=y
    y=r
print('result=',y)

 一元人民币兑换成一分、两分、五分的个数

i,j,k=0,0,0
count=0
for i in range(21):
    for j in range(51):
        k=100-5*i-2*j
        if k>=0:
            count+=1
print(count)

break语句

#判断是素数
from math import sqrt
j=2
while j<=100:
    i=2
    k=sqrt(j)
    while i<=k:
        if j%i==0:break
        i=i+1
        if i>k:
            print(j,end=' ')
    j+=1