（三）Python基础6：表达式

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6-exp.py

# 1.条件语句

num = 20
if num > 18:
    print('num > 18')


num = 17
if num > 18:
    print('num > 18')
else:
	print('num < 18')


num = 18
if num > 18:
    print('num > 18')
elif num == 18:
	print('num == 18')
else:
	print('num < 18')



# 2.循环语句
l = ['a', 'b', 'c']
for v in l:
    print(v)


sum = 0
for x in range(101): # [0-100]
    sum = sum + x
print(sum)


sum = 0
n = 99
while n > 0:
    sum = sum + n
    n = n - 2
print(sum)


# 3. break
n = 1
while n <= 100:
    if n > 10: # 当n = 11时，条件满足，执行break语句
        break # break语句会结束当前循环
    print(n)
    n = n + 1


# 4. continue
n = 0
while n < 10:
    n = n + 1
    if n % 2 == 0: # 如果n是偶数，执行continue语句
        continue # continue语句会直接继续下一轮循环，后续的print()语句不会执行
    print(n)


# 注意：如果遇到死循环，Ctrl+C退出程序，或者强制结束Python进程