Python学习笔记(五)—LOOP 循环

来源：互联网发布：电脑性能测试软件编辑：程序博客网时间：2024/06/07 13:09

个人认为Python基础学习直到LOOP才算真正开始。

循环有While， do-while，和for()

比如while

我们要输出100条“you are my sunshine ”可以表达如下：

count = 0while count< 10:    print("you are my sunshine "),    count = count + 1

输出结果如下：

前面我已经讲过，print后面加逗号(，)表示输出字符串不会换行。

while关键字行行尾一定要加：

while循环用在计算中：

import randomnumber1 = random.randint(0,10)number2 = random.randint(0,10)if number1<number2:    number1,number2 = number2,number1answer = eval(raw_input("what is "+str(number1)+"-"+str(number2)+" = "))while number1 - number2 != answer:   answer = eval(raw_input("you enter the wrong answer,please try it again !"+str(number1)+"-"+str(number2)+"?"))print("you got it !")

再比如猜数字：

import randomnumber = random.randint(0,10)guess = -1while guess != str(number):    guess = eval(raw_input("please enter the right number :"))    print(guess)    if str(guess) == str(number):        print("yes,you got the right number",number)    elif str(guess) > str(number):        print("please enter a lower number !")    else:        print("please enter a larger number !")

或者不需要str

import randomnumber = random.randint(0,10)guess = -1while guess != number:    guess = eval(raw_input("please enter the right number :"))    print(guess)    if guess == number:        print("yes,you got the right number",number)    elif guess > number:        print("please enter a lower number !")    else:        print("please enter a larger number !")

LOOP循环中我们最关心的就是耗时时长了，计算耗时的函数是time.time(),需要加import time

比如：

start = time.time()...end = time.time()time_elapsed = int(end - start)

应用到猜数字程序中：

import randomimport timenumber = random.randint(0,10)guess = -1start = time.time()while guess != number:    guess = eval(raw_input("please enter the right number :"))    print(guess)    if guess == number:        print("yes,you got the right number",number)    elif guess > number:        print("please enter a lower number !")    else:        print("please enter a larger number !")   end = time.time()time_elapsed = str(end - start)print("Time elapsed "+time_elapsed+" seconds")

for循环

输出顺序元素

for v in range(4,8):    print(v)

包含4不包含8。

间隔输出

for v in range(4,20,2):    print(v)

逆序输出

for v in range(20,4,-2):    print(v)

累和：

sum = 0for i in range(10):    sum = sum+i    print(sum)

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