score=10
if score>60:
print('yes')
else:
print('no')
score=10
if score>=90:
print('A')
elif score>=60:
print('B')
else:
print('C')
分支结构只能命中一个分支,python中没有switch-case语句
一般情况下,else用的不多
i=3
while i>0:
print(i)
i-=1
else:
print('循环结束')
通常用来遍历列表、元组、集合和字典数据类型
mylist=[1,3,5,7,9]
for i in mylist:
print(i)#1,3,5,7,9
mylist={
'name1':'user1',
'name2':'user2',
'name3':'user3'
}
for i in mylist:
print(i,mylist[i])
#name1 user1
#name2 user2
#name3 user3
str='linux'
for i in str:
print(i)#l i n u x
注意break和continue的区别
i=0
while i<10:
if i==5:
break#结束本层循环
print(i)
i+=1
#0 1 2 3 4
i=0
while i<10:
if i==5:
i+=1#不加这句的话i===5,一直处于continue陷入死循环
continue#结束本次循环
print(i)
i+=1
#0 1 2 3 4 6 7 8 9
以九九乘法表为例说明while和for的两种方法
i=1
while i<=9:
j=1
while j<=i:
print(str(j)+'*'+str(i)+'='+str(j*i),end=' ')
j+=1
i+=1
print('')
for i in range(1,10):
for j in range(1,i+1):
print('{0}*{1}={2}'.format(j,i,j*i),end=' ')
print(' ')
def myfunction():
pass;#没有这一句会报错
a=10
b=a
del a
print(b)#10
print(a)#报错
mylist=[1,3,5]
del mylist[0]
print(mylist)#[3,5]
del mylist
print(mylist)#报错——name 'mylist' is not defined
for i in range(5):
print(i)#0 1 2 3 4
mylist=[1,3,5,7,9]
print(len(mylist))#5
str='hello world'
print(len(str))#11
通常用一下for i in 来遍历
mylist=[1,3,5,7,9]
for i in range(len(mylist)):
print(i)#0 1 2 3 4(列表下标)
print(i,mylist[i])
'''
0 1
1 3
2 5
3 7
4 9
'''
x=[1,3,5]
y=['linux','h5','python']
z=zip(x,y)
dc=dict(z)
print(z)#结果为
print(dc)#结果为{1: 'linux', 3: 'h5', 5: 'python'}
mylist=['name1','name2','name3']
for key,val in enumerate(mylist):
print(key,val)
'''拿到下标和对应的值
0 name1
1 name2
2 name3
'''