1. if 语句
x = int(input("please enter a number: "))
if x < 0:
x = 0
print('Negative changed to zero')
elif x == 0:
print('ZERO')
elif x == 1:
print('SINGLE')
else:
print('MORE')
关注“if...elif...else”的格式
关注“elif” = else if
2. for语句
#举例
>>> for i in range(5):
... print(i)
...
0
1
2
3
4
range()是一个内置函数,所生成的链表中不包括范围中的结束值。
也可以让 range() 操作从另一个数值开始,或者可以指定一个不同的步进值(甚至是负数,有时这也被称为 “步长”)
range(5, 10)
5 through 9
range(0, 10, 3)
0, 3, 6, 9
range(-10, -100, -30)
-10, -40, -70
range() 和 len() 实现迭代:
>>> a = ['Mary', 'had', 'a', 'little', 'lamb']
>>> for i in range(len(a)):
... print(i, a[i])
...
0 Mary
1 had
2 a
3 little
4 lamb
3. while 语句
for i in range(1,10):
for j in range(1,1+i):
print(j,"*",i,"=", i*j, end=" ")
print()
结果:
1 * 1 = 1
1 * 2 = 2 2 * 2 = 4
1 * 3 = 3 2 * 3 = 6 3 * 3 = 9
1 * 4 = 4 2 * 4 = 8 3 * 4 = 12 4 * 4 = 16
1 * 5 = 5 2 * 5 = 10 3 * 5 = 15 4 * 5 = 20 5 * 5 = 25
1 * 6 = 6 2 * 6 = 12 3 * 6 = 18 4 * 6 = 24 5 * 6 = 30 6 * 6 = 36
1 * 7 = 7 2 * 7 = 14 3 * 7 = 21 4 * 7 = 28 5 * 7 = 35 6 * 7 = 42 7 * 7 = 49
1 * 8 = 8 2 * 8 = 16 3 * 8 = 24 4 * 8 = 32 5 * 8 = 40 6 * 8 = 48 7 * 8 = 56 8 * 8 = 64
1 * 9 = 9 2 * 9 = 18 3 * 9 = 27 4 * 9 = 36 5 * 9 = 45 6 * 9 = 54 7 * 9 = 63 8 * 9 = 72 9 * 9 = 81