Python的基本操作——2.1 控制流

桃扇骨 2021-09-27 04:00 269阅读 0赞

视频教程来自：www.zygx8.com，谢谢！

## 一、 If 语句 ##

if 条件：
        语句1
    elif 条件2：
        语句2
    else
         语句3

范例：

# if-猜数字
    number=66
    guess=int(input('Enter an intenger: '))
    
    if guess==number:
        print('you are right!')
    elif guess<number:
        print('the number is higher than that')
    else:
        print('the number is lower than that')

## 二、For 语句 ##

# for语句
    #1
    for i in range(1,10):
        print(i)
    else:
        print('done')
    #2
    a_list=[1,2,4,5,8]
    for i in a_list:
        print(i)
    
    #3
    a_tuple=(2,3,5,6)
    for i in a_tuple:
        print(i)
    
    ano_tuple=('a','b','c')
    for i in ano_tuple:
        print(i)
    #4
    a_dict={'Tom':11,"May":23}
    for ele in a_dict:
        print(ele)
        print(a_dict[ele])

## 三、while 语句 ##

# while 语句
    number=66
    flag=True
    while flag:
        guess=int(input('Enter an intenger: '))
    
        if guess==number:
            print('you are right!')
            flag=False
        elif guess<number:
            print('the number is higher than that')
        else:
            print('the number is lower than that')
    print('done!')

## 四、range 语句 ##

# range 语句:range(1,10)，实际上是从1-9，包括前面不包括后面
    # 同猜数字，限定次数时
    number=66
    chances=3 #3次机会
    for i in range(1,chances+1):
        guess = int(input('Enter an intenger: '))
        if guess == number:
            print('you are right!')
            flag = False
        elif guess < number:
            print('the number is higher than that')
            print('you still have '+str(chances-i)+' chances')
        else:
            print('the number is lower than that')
            print('you still have ' + str(chances - i) + ' chances')
    print('done!')

## 五、其他 ##

1. break：跳出整个循环

2. continue：忽略循环剩下的部分，重新回到for的部分

3. pass：相当于什么都没有

#pass
    list1=[0,1,2]
    for i in list1:
        if not i:
            continue
        print(i) 
    # i=0, if生效，执行continue，忽略循环体剩余部分，进入下一次循环i=1
    # i=1, if不满足，继续执行print；i=2时一样的道理
    # 【注意】：python中，布尔型属于int，其实就是1-0
    
    for i in list1:
        if not i:
            pass
        print(i)
    # i=0，if生效，执行pass，pass相当于什么都没有，所以继续执行print

最后我想吐槽一下，为什么我的程序代码乌漆抹黑的？？？为什么？？？

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[70]: /images/20210923/d7a69fa6208d46c9852b0131c8daec94.png