Python3学习笔记5:字符串操作、dict字典的合理使用----购物车优化之商家端

学习Python3,坚持每一次学习都有一点点知识的积累,瞄准目标gogogo!这次仍然是练习,增加字符串操作、dict字典的合理使用,使用了一些稍微复杂的逻辑(题目源自老男孩)

购物车程序商家入口

  可以增加商品;

  修改商品。

先上代码:

#Author wsp
##商家程序,要求如下:
    #可以添加商品,修改商品价格
print("这里是商品后台系统".center(70, "#"))

while True:
    #只读方式打开文件
    goods_file_r = open("goods.txt", "r")
    lines = goods_file_r.readlines()
    #涉及到去重,使用字典
    goods_list = {}
    print("当前商品列表如下:")
    for line in lines:
        goods_line = line.split(" ")
        if goods_line.__len__() == 2:
            goods_list[goods_line[0].strip()] = goods_line[1].strip()
            print("{name} {cost}".format(name=goods_line[0].strip(), cost=goods_line[1].strip()))
    #关闭文件句柄
    goods_file_r.close()
    choice = input("商品信息显示完成,请选择操作,1-》增加商品;2-》修改商品:")
    if choice.isdigit():
        choice = int(choice)
        ##增加商品
        if choice == 1:
            new_goods_name = input("请输入要增加的商品名:")
            if len(new_goods_name) != 0 and not goods_list.__contains__("new_goods_name"):
                while True:
                    new_goods_cost = input("请输入商品价格:")
                    if new_goods_cost.isdigit():
                        new_goods_cost = int(new_goods_cost)
                        goods_list[new_goods_name] = new_goods_cost
                        #写的方式打开文件
                        goods_file_w = open("goods.txt", "w")
                        for goods_new in goods_list:
                            line = "{name} {cost}\n".format(name=goods_new, cost=goods_list[goods_new])
                            goods_file_w.write(line)
                            #1goods_file.write('\n')
                        print("增加商品{name},金额为{cost}".format(name=new_goods_name, cost=new_goods_cost))
                        #关闭写文件句柄
                        goods_file_w.close()
                        break
                    else:
                        print("请输入正确的价格")
                        continue
            else:
                print("请输入正确的商品名称")
        #修改商品
        elif choice == 2:
            new_goods_name = input("请输入要修改的商品名:")
            if goods_list.__contains__(new_goods_name):
                while True:
                    new_goods_cost = input("请输入商品价格:")
                    if new_goods_cost.isdigit():
                        new_goods_cost = int(new_goods_cost)
                        goods_list[new_goods_name] = new_goods_cost
                        # 写的方式打开文件
                        goods_file_w = open("goods.txt", "w")
                        for goods_new in goods_list:
                            goods_file_w.writelines("{name} {cost}".format(name=goods_new, cost=goods_list[goods_new]))
                            goods_file_w.write('\n')
                        goods_file_w.close()
                        break
                    else:
                        print("请输入正确的价格")
                        continue
            else:
                print("商品{new_goods_name}不存在请输入正确的商品名称".format(new_goods_name=new_goods_name))
    else:
        print("请输入正确的数字!")

要点(今天有点事明天更新要点。。。。。):

 

 

string相关的使用方法:

#Author wsp
name = "wang wang peng"
print(name.capitalize())
print(name.center(50, "-"))
print(name.encode())
print(name.endswith("peng"))
print(name.expandtabs(tabsize=30))
print(name.find("wang"))#找到对应的索引
print(name.isalnum())
print(name.isalpha())
print("1a212".isdecimal())#判定是否是十进制
print("1A".isidentifier())#判断是否是合法的标示符,也就是能否当做变量名
print("a".islower())#是否小写
print("1212".isnumeric())#是否只含有数字
print(" ".isspace())#是否是空格
print('i like you!'.join("=="))
print("+".join(['1','2','3']))
print(name.ljust(50,"*"))#右侧补充
print(name.rjust(50,"*"))#左侧补充
print("AAAA".lower())
print("asdasd".lstrip())#去掉左边的空格或者回车

p = str.maketrans("abcdef","123456")
print("i like you ".translate(p))

print("asdsadasd".replace("a","A",1))
print("asdsadasd".rfind("d"))#从右开始找,第一个d的位置
print("i like you ".split("i"))#分割字符串,i为分隔符

print("I like you".swapcase())#大写变小写

dict字典:

#Author wsp
#字典相关
    #字典是无序的
    #key是唯一的,天生去重
#定义:
name_map = {
    "james": "123456", "ad": "123123"
}
print(name_map)
name_map["james"]
print(name_map)
del name_map["ad"]
name_map.pop("james")
#name_map.popitem()

name_map.get("ad")#此方法比较简单,如果没有在字典里,也不会报错
"ad" in name_map #判定是否有ad存在
name_map1 = {
    "james": "123456", "ad": "123123"
}
print(name_map1.items())
print(dict.fromkeys([1,2,3],"keys"))

#有个坑
ff= dict.fromkeys([1, 2, 3], [1, {"name": "alex"}, 444])
print(ff)
ff[2][1]['name']= 'jack'
print(ff)

 

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