day1 -- Python变量 注释 格式化输出字符串 input if while for

1.python变量

不需要声明类型，直接 变量名 = 变量值，如 ： name = "hahaha"

2.注释：

单行注释，前面加 #，如# print(info)

多行注释，用三组单引号或者三组双引号包围起来，如'''print(info)'''"""print(info)"""

注意：三组单引号包围起来的变量可以直接格式化输出，看下面的3的第一个案例

3.格式化输出字符串

1 info = '''name is %s and age is %s''' % (name, age)2 info2 = "name2 is {n} and age2 is {a}".format(n=name, a=age)3 info3 = "name3 is {0} and age3 is {1}".format(name, age)

4.input()方法默认输入存储的类型是str，如果需要转换类型可以使用类型转换函数如int()，如：

age = int(input("input your age:"))

5.if、elif、else：注意顶格对齐

my_age = int(input("guess my age:"))if my_age > 60:print("you guess error")elif my_age == 60:print("you guess right")else:print("hhh")

6.while

count = 0while count < 3:age = int(input("guess my age:"))if age < 50:print("sorry, your answer is error")elif age == 50:print("{a} is right".format(a=age))breakelse:print("hhh")count += 1# while条件不符合，则走else里面的else:print("you have tried too many times!!!")

7.for

for i in range(3):age = int(input("guess my age:"))if age < 50:print("sorry, your answer is error")elif age == 50:print("{a} is right".format(a=age))breakelse:print("hhh")# for正常结束，则走else里面的，# 如果for被break，则不走else里面的else:print("you have tried too many times!!!")

tip：range方法看下面

8.range方法

# 起始，终点，步长，输出0,2,4,6,8for i in range(0, 10, 2):print("i = ", i)# 默认步长为 1，即输出1-99for j in range(99):print(i)