顺序、分支、循环
注意：python中没有switch语句

1、分支

注意：# ‘’ 0 None 默认为False

age = 17
if age > 4:
    print("age > 4 ")
    print("....")
if age >= 18:
    print("age >= 18")
    print("....")
else:
    print("age < 18")
if 0 < age < 17:
    print("0 < age < 17")
elif 17 <= age < 30:
    print("age >=17 and age<30")
    print("....")
elif age < 0 or age >= 30:
    print("age < 0 or age >= 30")

2、循环

2.1、while

row = 1
while row <= 9:
    col = 1
    while col <= row:
        print("%d * %d = %d" % (col, row, col * row), end="\t")
        col += 1
    row += 1
    print("")
-------------------
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

i = 0
while i < 10:
    if i % 2 == 0:
        i += 1
        continue
    if i == 7:
        break
    print(i)
    i += 1

2.2、for

for i in range(0, 10):
    print(i)
for i in [1, 2, 3, 6]:
    print(i)
for i in 'hello':
    print(i)