while
while
while
whlie 条件:
循环体
如果条件为真则运行循环体,如果条件为假,则不运行
案例1:输出1到10,指定任意数字不输出
a = 0 while a<11: a+=1 if a == 8: continue print(a)
结果:
1234567910
案例2:输出1到100的相加的和
sum = 0 num = 0 while num <100: num += 1 sum = sum + num print(sum)
结果:
5050
案例3:猜迷输入数字,当需要退出时输入q即可退出
while True: a = input("请输入数字") if a == 'q': print("笨蛋") break elif int(a)<66: print("小了") continue elif int(a) > 66: print("大了") continue elif int(a) == 66: print("等于") break
案例4:用户登陆(三次输错机会)且每次输错误时显示剩余错误次数(提示:使用字符串格式化)
num = 3 while num >0: name = input("输入账号") password = input("输入密码") if name == 'www' and password == 123456: msag = '恭喜您登陆成功' print(msag) else: num -= 1 msg = '您输入的有误,剩余输入次数还有%s,'%(num) print(msg)
案例5:求1-2+3-4+5 ... 99的所有数的和
a = 0 num = 1 while num < 100: if num % 2 == 1: a += num num += 1 else: a -= num num += 1 print(a)
案例6:给用户三次猜测机会,如果三次之内猜测对了,则显示猜测正确,退出循环,如果三次之内没有猜测正确,则自动退出循环,并显示‘太笨了你....’。
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
num = 0 while num<3: a = int(input("请输入数字")) if a<66: print("小了") continue elif a > 66: print("大了") continue elif a == 66: print("等于") break num += 1 if num == 3: print("笨蛋") break 要注意这三次循环的累积的位置,若是先进行循环判断会在第三次输入时出现三次输入的错误
双while循环
案例1:
使用#号输出一个长方形,用户可以指定宽和高,如果长为3高为4,则输出一个横着有3个#号竖着有4个#号的长方形
he = int(input("高:")) we = int(input("宽:")) a = 1 while a < he: b = 1 while b <= we: print("#",end='') #end末尾不换行 b +=1 print("") a+=1
这是一个while嵌套的案例,两个循环分别对应着两个变量,内循环对应着一个变量要输出多少次以及输出的格式,而外循环对应着要进行多少次输出
案例2:
如何输出如下的直角三角形,用户指定输出行数(如果上下翻转,如何实现?)
*
**
***
****
*****
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
正序输出: he = int(input("高:")) j = 1 while j <=he: print("*"*j) j +=1 倒序输出: he = int(input("高:")) j = 1 while j <=he: print("*"*he) he -=1
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
正序输出 num = input("输出数字") a = 0 while a<=num: b = 0 while b <=a: print("*",end='') b+=1 print("") a+=1 倒序输出 num = int(input("输出数字")) a = 0 while a<num: b = 0 while b <num: print("*",end='') b+=1 print("") num -= 1
案例3:打印9*9乘法口诀表
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
num = 1 while num <=9: num1 = 1 while num1<=num: print(str(num1)+"*"+str(num)+"="+str(num1*num),end='\t') num1 +=1 print("") num +=1
posted on 2018-12-28 22:05 🐳️南栀倾寒🐳️ 阅读(181) 评论(0) 编辑 收藏 举报