Python之‘’控制流‘’

一、if语句

格式：

i1 = 3

if i1 > 4:

    print('yes you are right')

elif 0 < i1 < 4:

    print('im dont konw')

else:

    print('no you are wrong')

注意if、elif以及else后面的（:）符号，我们通过它告诉Python下面跟着一个语句块。

二、while语句

number = 23

running = True

while running:

    guess = int(input('enter an integer:'))

    if guess == number:

        print('congratulations,you guessed it')

        running = False

    elif guess < number:

        print('no,it is a little lower than that')

    else:

        print('no,it is a little higher than that ')

else:

    print('the while loop is over')

print('done')

输出结果：

enter an integer:22
no,it is a little lower than that
enter an integer:24
no,it is a little higher than that
enter an integer:23
congratulations,you guessed it
the while loop is over
done

注意：在Python2.x版本中输入使用的是raw_input而在Python3.x版本中输入使用的是input。并且后面都要跟冒号。

三、for循环

格式：for...in

for i in range(1,5):

    print(i)

else:

    print('the loop is over')

结果：

C:\Python36\python.exe C:/Users/蔡瑞/7.py

1

2

3

4

the loop is over

Process finished with exit code 0

注意：range(1,5)只是输出1-4没有5。还有，else部分是可选的，如果包含else，它总是在for循环结束后执行一次，除非遇到break语句。

for循环在这个范围内递归，这就相当于把序列中的每个数（或对象）赋值给i，一次一个，然后以每个i的值执行这个程序块。

Programming is fun

When the work is done

if you wanna make your work also fun:

　　use Python

巴特西

Python之‘’控制流‘’

一、if语句

二、while语句

三、for循环

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