print('Hello,world!')
name = 'cc'
name2 = name
name = 'cuichen'
print(name,name2)

name2 = name 只是通过name指向‘cc’，name2并不指向name，所以即使name指向改变，name2并不改变



理解变量在计算机内存中的表示：

a = ‘abc’

当我们运行以上代码时，Python解释器干了两件事，1.在内存中创建了一个‘ABC’字符串，2.在内存中创建了一个名为a的变量，并把他指向‘ABC’




for循环可以直接让代码循环执行执行规定的次数，例子如下：

cc_age = 23
for i in range(3):
    age = int(input('His age is :'))
    if age == cc_age:
        print('Congratulation!')
        break
    elif age > cc_age:
        print('Too big!')
    else:
        print('Too small!')
else:
        print('You have too many times Fuck off....')

for循环还可以用于迭代：

for i in range(0,10,2):#步长为2
    print('-----------',i) 

多行打印，例子如下：

apple = input('apple:')
number = int(input('number:'))
print(type(number))
qwe = '''
--------qwe---------
apple:%s
number:%d
'''%(apple,number)
print(qwe)

cc_age = 23
count = 0 #count 代表计数器
while count <  3:
    age = int(input('His age is :'))
    if age == cc_age:
        print('Congratulation!')
        break
    elif age > cc_age:
        print('Too big!')
    else:
        print('Too small!')
    count += 1  #等于count = count+1    计数器
else:
        print('You have too many times Fuck off....')

for i in range(10):
    print('-------------------',i)
    for j in range(10):
        print(j)
        if j > 5 :
            break