Python基础

# 向控制台输出内容结束后,不换行
print("*",end="")
# 自带换行
print("")
%d 以十进制输出数字
%x 以十六进制输出数字 

name_list = ["zhangsan", "lisi", "wangwu"]
# API
In [1]: name_list.
name_list.append   name_list.count    name_list.insert   name_list.reverse
name_list.clear    name_list.extend   name_list.pop      name_list.sort
name_list.copy     name_list.index    name_list.remove 

info_tuple = ("zhangsan", 18, 1.75)
info_tuple = ()
# 元组中 只包含一个元素时，需要在元素后面添加逗号
info_tuple = (50, )  # 不加,类型为int
# API
info.count  info.index

list(元组) 

tuple(列表)

len(列表)

# API
In [1]: xiaoming.
xiaoming.clear       xiaoming.items       xiaoming.setdefault
xiaoming.copy        xiaoming.keys        xiaoming.update
xiaoming.fromkeys    xiaoming.pop         xiaoming.values
xiaoming.get         xiaoming.popitem    
# 字典的遍历
for k in xiaoming:
    print("%s - %s" % (k, xiaoming[k]))

card = [{"name": "小胡",
         "age": 18},
        {"name": "小张",
         "age": 19}]
for ren in card:
    print(ren)

num_str = "0123456789"

# 1. 截取从 2 ~ 5 位置 的字符串
print(num_str[2:6])

# 2. 截取从 2 ~ `末尾` 的字符串
print(num_str[2:])

# 3. 截取从 `开始` ~ 5 位置 的字符串
print(num_str[:6])

# 4. 截取完整的字符串
print(num_str[:])

# 5. 从开始位置，每隔一个字符截取字符串
print(num_str[::2])

# 6. 从索引 1 开始，每隔一个取一个
print(num_str[1::2])

# 倒序切片
# -1 表示倒数第一个字符
print(num_str[-1])

# 7. 截取从 2 ~ `末尾 - 1` 的字符串
print(num_str[2:-1])

# 8. 截取字符串末尾两个字符
print(num_str[-2:])

# 9. 字符串的逆序（面试题）
print(num_str[::-1])
print(num_str[-1::-1])

for 变量 in 集合:
    
    循环体代码
else:
    没有通过 break 退出循环，循环结束后，会执行的代码

students = [
    {"name": "阿土",
     "age": 20,
     "gender": True,
     "height": 1.7,
     "weight": 75.0},
    {"name": "小美",
     "age": 19,
     "gender": False,
     "height": 1.6,
     "weight": 45.0},
]

find_name = "阿土"

for stu_dict in students:

    print(stu_dict)

    # 判断当前遍历的字典中姓名是否为find_name
    if stu_dict["name"] == find_name:
        print("找到了")

        # 如果已经找到，直接退出循环，就不需要再对后续的数据进行比较
        break

else:
    print("没有找到")

print("循环结束")

def demo(num, *args, **kwargs):

    print(num)
    print(args)
    print(kwargs)

demo(1, 2, 3, 4, 5, name="小明", age=18, gender=True)

def demo(*args, **kwargs):

    print(args)
    print(kwargs)


# 需要将一个元组变量/字典变量传递给函数对应的参数
gl_nums = (1, 2, 3)
gl_xiaoming = {"name": "小明", "age": 18}

# 会把 num_tuple 和 xiaoming 作为元组传递个 args
# demo(gl_nums, gl_xiaoming)
demo(*gl_nums, **gl_xiaoming)

def measure():
    a11 = 1031
    a22 = 11
    return a11, a22
s, d = measure()
print(s)
print(d)
print(measure())

a = 6
b = 100
# 解法一
c = a
a = b 
b = c
# 解法二
a = a + b
b = a - b
a = a - b
# 解法三 元祖()可以省略
a , b = (b, a)
a , b = b, a

def demo(num_list):
    num_list.append(9)
    print(num_list)
num_list = [1, 2, 3]
demo(num_list)
print(num_list)
# 运行结果
[1, 2, 3, 9]
[1, 2, 3, 9]

def demo(num,num_list = True):

def sum_numbers(*args):
num = 0
# 遍历 args 元组顺序求和
for n in args:
    num += n

return num
print(sum_numbers(1, 2, 3))

$ which python3

#! /usr/bin/python3  

$ chmod +x cards_main.py

./cards_main.py