本节内容
1、认识while循环
2、while循环的运用
3、嵌套循环:循环套循环
1、认识while循环
break # 跳出当前整个循环
continue # 跳出当次循环,继续下次循环
1 while 判断条件: #当while满足条件时,程序会一直循环
2 执行语句... 3 else: #当while正常循环完成后,,程序才会进行else 注:break会终止while整个循环,所以程序不会进行else;而continue是跳过当次循环继续下次循环,所以程序会进行else
4 执行语句...
2、while循环的运用
用户输入一个值,猜出正确的年龄
1 age = 60
2 while True: 3 guess_age = int(input("年龄:")) 4 if guess_age == age: 5 print("恭喜你!猜对了!") 6 break
7 elif guess_age > age: 8 print("猜大了!") 9 else: 10 print("猜小了!") 11 else: 12 print("End")
3、嵌套循环:循环套循环
(1)使用 # 号输出一个长方形,用户可以指定宽和高。列如:长为3,高为4,就输出一个横着有3个#号,竖着有4个#号的长方形
1 height = int(input("高度:")) 2 width = int(input("宽度:")) 3 num1 = 1
4 while num1 <= height: 5 num2 = 1
6 while num2 <= width: 7 print("#",end="") 8 num2 += 1
9 num1 += 1
10 print() 11 else: 12 print("End")
(2)用while循环输入“九九乘法表”
1 num1 = 1
2 while num1 <= 9: 3 num2 = 1
4 while num2 <= num1: 5 num3 = num2 * num1 6 print(num1, "*", num2, "=", num3, end=" ") 7 num2 += 1
8 print() 9 num1 += 1
10 else: 11 print("九九乘法表")
(3)用for循环写“九九乘法表”
1 for a in range(1,10): 2 for b in range(1,a+1): 3 c = a*b 4 print(b,"*",a,"=",c,sep="",end=" ") 5 else: 6 print()
(4)用while循环输出1-100的数,并每10个数换一行
1 方法一: 2 a =1 3 b =1 4 while a<=10: 5 c= (a-1)*10 6 b=1 7 while b<=10: 8 print(c+b,end=" ") 9 b+=1 10 else: 11 print() 12 a+=1
1 方法二: 2 a = 1 3 while a <= 100: 4 print(a,end=" ") 5 if a%10==0: 6 print() 7 a+=1
(5)用for循环写1-100的数,每10个数换一行
1 for a in range(10): 2 c = (a)*10 3 for b in range(1,11): 4 print(b+c,end="") 5 else: 6 print()
(6)用for循环写用户验证,用户有4次输入错误的机会
1 name = "jxj" 2 pwd = "123456" 3 for a in range(1,5): 4 name_in = input("请输入用户名:") 5 pwd_in = input("请输入密码:") 6 if name_in==name and pwd_in==pwd: 7 print("登陆成功!") 8 else: 9 print("用户名或密码错误!") 10 print("你还有",4-a,"次机会!")