Python第二课，流程控制

选择流程

# 条件判断
# 单分支
b = False
if b:
    print('输出a')
    pass  # 空语句

# 双分支
if b:
    print('输出b')
    pass  # 空语句
else:
    print('输出c')
    pass  # 空语句

# 多分支
a = 1
if a > 2:
    print('输出1')
    pass  # 空语句
elif a > 1:
    print('输出2')
    pass  # 空语句
else:
    print('输出3')
    pass  # 空语句

循环流程

# 循环流程
# while循环
i = 1
while i < 10:
    j = 1
    while j <= i:
        print('%i * %i = %i ' % (j, i, i * j), end=' ')
        j += 1
        pass
    i += 1
    print()
    pass

# 等腰三角形
r = 1
c = 10  # 总共多少行
while r <= c:
    j = 1
    while j <= c - r:  # 输出空格
        print(' ', end='')
        j += 1
        pass
    k = 1
    while k <= 2 * r - 1:  # 输出*
        print("*", end='')
        k += 1
        pass
    print()
    r += 1
    pass

# for循环
# 遍历字符串
name = 'zhangsan'
for i in name:
    print(i, end=' ')
    pass
print()
# range 类型表示不可变的数字序列，通常用于在 for 循环中循环指定的次数。
# 遍历对象求1到10的和
count = 0
for i in range(0, 10):
    count += i
    pass
print(count)

# break 退出循环 和 continue 跳过本次循环
age = 18;
while age:
    if age < 12:  # 当age小于12时跳过循环
        continue
        pass
    else:
        print(age)
        pass
    if age == 0:  # 当age等于18是退出循环
        break
        pass
    age -= 1
    pass