0826一些python基础练习

#！/usr/bin/python3
#coding=utf-8

#num1,num2是形参
def sum_2_num(num1,num2):
    num1 = num1 - 10
    result = num1 + num2

    print("%d + %d = %d" % (num1, num2, result))
    return result

# 50,20是实参
a = 50
a = sum_2_num(a,20)
print(a)

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#!/usr/bin/python3
# coding=utf-8

a = 50
print(id(a))
b = a
print(id(b))
a = a - 10
print(id(a))

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#!/usr/bin/python3
# coding=utf-8

# 可变数据类型
arr = [1, 2, 3]
print(id(arr))
arr[0] += 1
print(id(arr))

print('-' * 50)
a = 1
print(id(a))
a = "hello"
print(id(a))
a = [3, 2, 1]
print(id(a))
demo_list = [1, 2, 3]

print("定义列表后的内存地址 %d" %id(demo_list))

demo_list.append(999)
print(demo_list)
#下标
demo_list.pop(0)
print(demo_list)
#remove里面的参数是value
demo_list.remove(2)
demo_list[0] = 10
print(demo_list)

print("修改数据后的内存地址 %d" % id(demo_list))

demo_dict = {"name" : "小明", "sex" : True}
print("定义字典后的内存地址 %d" % id(demo_dict))

demo_dict["age"] = 18
demo_dict["name"] = "laowang"
print(demo_dict)
print("修改数据后的内存地址 %d" % id(demo_dict))

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#!/usr/bin/python3
# coding=utf-8

num = 10

def demo1():
    global num
    num += 3
    print(num)

def demo2():
    print(num)

demo1()
demo2()

print("over")

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#!/usr/bin/python3
# coding=utf-8

i = 10
print(type(i))
arr = [1, 2, 3, 2, 4, 1, 2]
print(len(arr))
print(arr.count(2))

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#写一个简单的for循环，从1打印到20，横着打为1排

for i in range(1, 21):
    print(i, end=' ')

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#写一个say_hello函数打印多次hello并给该函数加备注（具体打印几次依靠传递的参数），
#然后调用say_hello，同时学会快速查看函数备注快捷键，及如何跳转到函数实现快捷键

def say_hello(x):
    """打印x次hello"""
    for i in range(x):
        print("hello")

#查看快捷键 CTRL+Q
say_hello(6)

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#!/usr/bin/python3
# coding=utf-8

arr = [7, 8, 9, 10, 20, 8, 9, 19, 10, 8]

#通过value反复索引
print(arr.index(8, 6))
#新增
arr.append(1)
print(arr)
arr.insert(2, 3)
print(arr)
arr.extend([1, 2, 3])
print(arr)
#修改
arr[0] = -1
print(arr)
#删除
print(id(arr))
del arr[0]
print(id(arr))
print(arr)

#排序
arr.sort(reverse=True)
print(arr)

arr.clear()
# 列表为空的时候，如果用arr[0]=3给列表赋值会报错，要用append

#列表生成式 简单使用
a = [x for x in range(10)]
print(a)
b = []
for x in range(10):
    b.append(x)
print(b)

#2个for循环
a = [j for i in range(10) for j in range(i)]
print(a)
a = [[col * row for col in range(5)]for row in range(5) ]
print(a)
a = [j for x in a for j in x] #2维列表转1维列表
print(a)
#只有if时 只会筛选偶数
a = [x for x in range(10) if x % 2 == 0]
print(a)

#切片
print(a[3:6])
print(a[-2])
print(a[-5:-2])

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#!/usr/bin/python3
# coding=utf-8

info_tuple = (3, 4)
print(type(info_tuple))

print(len(info_tuple))

info_tuple = ("xiaoming", 21, 1.85)

#格式化字符串后面的‘（）’本质上就是元组
print("%s 年龄是 %d  身高是 %.2f" % ("xiaoming", 21, 1.85))
info_str = "%s 年龄是 %d 身高是 %.2f" % info_tuple

print(info_str)

#列表转元组
info_list = [1, 2, 3]
print(id(info_list))
info_tuple = tuple(info_list)
print(info_tuple)
#元组转列表
info_list = list(info_tuple)
print(info_list)
print(id(info_list))

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0826一些python基础练习