变量和简单的数据类型

一.变量、字符串、print、类型转换、运算符

message = "Hello Python world" #字符串变量
a,b,c = 9,9,3

print(message)
print("apple"+str(4))
print(1.4+int("1"))
print(a%4,b//4,c**2)

二.语句

1. while循环

condition = 1
while condition < 10:
  print(condition)
  condition = condition + 1

2. for循环

ex_list = [1,2,3,4,5]
for i in ex_list:
    print(i)
    print('inner of for')

• 可加参数step
• range的范围1~9：

for i in range(1,10):
    print(i)

3. if、elif、else

x=5
y=5
z=9
if x<5>4:
    print('x<5>4')
elif (x<5)<4:
    print(f'(x<5)<4:{x<5}')
else:
    print('else')

• x<y<z被解释为(x<y) and (y<z)
• f字符串：
  print(f'(x<5)<4:{x<5}')
  要在字符串中插入变量的值，可先在左引号前加f，再将变量放入花括号内