用户和登录的实现原理和过程

#1.统计小写英文字符出现的次数
def countchrnum(s):
    result={}
    for c in s:
        if c < 'a' or c > 'z':# 判断字母c < a 或者 c >z
            continue
        if c in result:
            result[c] += 1
        else:
            result[c] = 1
    return result
s='python test case'
print(countchrnum(s))

#实现用户登录和注册
#1.提示用户登录和注册
#2.注册流程 注意提示和字典处理
#3.登录过程 注意用户密码判断
#4.实现过注意函数定义和返回值
#5.代码优化 使用函数和字典的组合
usrinfo={}
def loginfunc():
    #登录函数
    uname = input('input user name:')
    pwd = input('input user pwd:')
    if uname not in usrinfo:
        print(f'user name {uname} not exist')
    elif pwd != usrinfo[uname]:
        print('passwd is error')
    else:
        print('login success')

def refunc():
    #注册函数
    uname = input('input user name:')
    pwd = input('input user pwd:')
    if uname in usrinfo:
        print('f{uname} exist,input again')
        return
    usrinfo[uname] = pwd
    print('user list',usrinfo)

def select_menu():
    tip = 'input [r] reg,\ninput [l] login:\n'
    while True:
        cmd = input(tip)
        if cmd == 'r':
            print('start reg')
            refunc()
        elif cmd == 'l':
            print('start login')
            loginfunc()
        elif cmd == 'q':
            break
        else:
            print('input error!')

def select_menu():
    tip = 'input [r] reg,\ninput [l] login:\ninput [q] exit:\n'
    opt_dict = {'r':refunc,'l':loginfunc}
    while True:
        cmd = input(tip)
        if cmd == 'q':
            break
        func= opt_dict.get(cmd)
        if func: #if func的值不为None 执行func函数
            func()


if __name__ == '__main__':
    select_menu()