1 """
 2 while  条件：
 3     满足条件
 4 #只要条件满足，会无限循环执行
 5 """
 6 i = 0
 7 sum = 0
 8 while i<=100:
 9     sum = sum + i
10     i += 1
11 print(sum)

 1 #无限次猜数字
 2 import random
 3 num = random.randint(1,100)
 4 count = 0
 5 flag = True
 6 while flag:
 7     guess_num = int(input("请输入你猜测的数字："))
 8     count += 1
 9     if guess_num == num:
10         print("猜中了！")
11         flag = False
12     else:
13         if guess_num > num:
14             print("大了")
15         else:
16             print("小了")
17 print("你猜测了",count,"次")

 1 #定义外层循环的控制变量
 2 i  = 1
 3 while i <= 9:
 4     #定义内层循环的控制变量
 5     j = 1
 6     while j <= i:
 7         print(f"{j}*{i}={j * i}\t",end=' ')
 8         j += 1
 9     i += 1
10     print() #print空内容，就是一个换行

"""
for 临时变量 in 待处理数据集：
    循环满足条件时执行的代码
"""
#case：查看字符串有几个a
string = "aaaaaaaaaa"
count = 0
for i in string:
    if i == 'a':
        count += 1
print(count)

#语法1    range(num)
#遍历：序列类型
for i in range(5):
    print(i)

#语法2 range(num1.num2)
#获得从1开始到5结束的序列(不包含5)
for j in range(1,5):
    print(j)

#语法3 range(num1.num2.step)
#获得从1开始到5结束的序列(不包含5)
#step为步长
for k in range(1,10,3):
    print(k)

count = 0
num = int(input("请输入一个数："))
for i in range(1,num):
    if i%2==0:
        count += 1
print(f"1~{num}一共有{count}个偶数")

for i in range(1,10):
    for j in range(1,i+1):
        print(f"{j}*{i}={j*i}\t",end=' ')
    print()