1.for

#逐个取数
a=['d','d']
b=''

for x in a:
    b+=x

print(b)

2.range

>>> a=[range(5)]
>>> a
[range(0, 5)]
>>> print(a)
[range(0, 5)]
>>> list(range(5))
[0, 1, 2, 3, 4]
>>> list(range(1,5))
[1, 2, 3, 4]
>>> list(range(1,5,2))
[1, 3]
>>> list(range(2,30,10))
[2, 12, 22]

a=list(range(2,30,10))
b=0

for x in a:
    b+=x

print(b)

3.while

n=1
s=0
while n<10:
    s+=n
    n+=1
    print("s:",s,"n:",n)

print(n)

break:

n=1
s=0
while True:
        s+=n
        n+=1
        print("s:",s,"n:",n)
        if s>30:
            break

print(n)

?continue:满足条件直接进行下一个循环

n=1
s=0
while True:
        s+=n
        print("s:",s,"n:",n)
        if s<10:
            continue
        if s>20:
            break
        n += 1

print(n)

?4.内置函数

Python 内置函数 | 菜鸟教程 (runoob.com)

>>> a=max
>>> a([1,4,7])
7
>>>

?5.自定义函数

def mm_c(a,b):
    if a>b:
        return a
    else:
        return b

if __name__=='__main__':      #相当于C语言中int main()
    c=mm_c(3,7)
    print(c)

注：python中可以返回多个值，例如:

return a,b

def mm(a,b=0)  #b=0为默认，当输入为一个数时

?一个小坑：

def add_h(a=[]):
	a.append('add')
	return a

c=add_h([1,2,3])
print("c:",c)

c=add_h()
print("c2:",c)

c=add_h()
print("c3:",c)

?所以尽量不用可变量作为参数

可以传入任意个数的参数? ? ? ? 用*表示? ? ? ?

def sum_a(*num):
    sum=0
    for i in num:
        sum+=i
    return sum

if __name__=='__main__':
    a=sum_a(1,3)
    b=sum_a(1,3,5)
    c=sum_a(7,7,7,7)
    print("a:",a,"\nb:",b,"\nc:",c)