7.3 字典Dictionary(键值对)
创建字典：demoDic={
"name":
"Tom",
"age":10,
"sex":1}
查看key对应的Value值：demoDic[
"name"]
删除字典中元素：del
demoDic[
"name"]
清空字典：demoDic.clear()
向字典中插入新的元素：demoDic[
"school"]=
"XD"
字典中元素可以是混合数据类型，且Key值不可变，Key元素可以为数字、字符串、元组(tuple)等，不能为List,字典中Key值必须唯一。
8 函数(Funciton)
8.1 函数定义声明
不带参数及带参数的函数定义
def
say_hi():
PRint(
"hi!")
say_hi()
say_hi()
def
print_two_sum(a,b):
print(a+b)
print_two_sum(3, 6)
def
repeated_strings(
str,times):
repeateStrings=str*3
return repeateStrings
getStrings=repeated_strings(
"hello
", 3)
print(getStrings)
在函数中声明全局变量使用global x
x=80
def
foo():
global x
print(
"x is
",str(x))
x=3
print(
"x changed
",str(x))
foo()
print(
"x is
",str(x))
8.2 参数
默认参数:调用函数时，未给出参数值，此时使用默认参数
def
repeated_string(string,times=1):
repeated_strings=string*times
return repeated_strings
print(repeated_string(
"hello
"))
print(repeated_string(
"hello
",4))
默认参数之后的参数也必须是默认参数
关键字参数:在函数调用时，指明调用参数的关键字
def
fun(a,b=3,c=6):
print(
"a:"+str(a)+
"
b:"+str(b)+
" c:"+str(c))
fun(1,4)
fun(10,c=8)
VarArgs参数:参数个数不确定情况下使用
带*参数为非关键字提供的参数
带**参数为含有关键字提供的参数
def
func(fstr,*numbers,**strings):
print(
"fstr:",fstr)
print(
"numbers:",numbers)
print(
"strings:",strings)
func(
"hello",1,2,3,str1=
"aaa",str2=
"bbb",str3=4)
9 控制流
9.1 if语句&for循环
if用法
num=36
guess=int(input(
"Enter
a number:"))
if
guess==num:
print(
"You
win!")
elif
guess<num:
print(
"The
number you input is smaller to the true number!")
else:
print(
"The
number you input is bigger to the true number!")
print(
"Done")
for用法，其中range(1,10)为1-9的数字，不包含10
for
i
in
range(1,10):
print(i)
else:
print(
"over")
且for对于List、Tupel以及Dictionary依然适用
a_list=[1,2,3,4,5]
for
i
in
a_list:
print(i)
b_tuple=(1,2,3,4,5)
for
i
in
b_tuple:
print(i)
c_dict={
"Bob":15,
"Tom":12,
"Lucy":10}
for
elen
in
c_dict:
print(elen+
":"+str(c_dict[elen]))
9.2 while循环
num=66
guess_flag=False
while
guess_flag==False:
guess=int(input(
"Enter
an number:"))
if
guess==num:
guess_flag=True
elif
guess<num:
print(
"The
number you input is smaller to the true number!")
else:
print(
"The
number you input is bigger to the true number!")
print(
"You
win!")
9.3 break&continue&pass
num=66
while
True:
guess=int(input(
"Enter
an number:"))
if
guess==num:
print(
"you
win!")
break
elif
guess<num:
print(
"The
number you input is smaller to the true number!")
continue
else:
print(
"The
number you input is bigger to the true number!")
continue
pass执行下一条语句，相当于什么都不做
a_list=[0,1,2]
print(
"using
continue:")
for
i
in
a_list:
if
not
i:
continue
print(i)
print(
"using
pass:")
for
i
in
a_list:
if
not
i:
pass
print(i)
