034丰富的else语句和简洁的with语句

求最大公约数

def showMaxFactor(num):
    count = num // 2
    while count > 1:
        if num % count == 0:
            print("%d最大的约数%d" % (num,count))
            break#如果弹出break弹出，后面的内容不再执行
        count -= 1
    else:
        print("%d是素数" % (num))

num = int(input("请输入一个数："))
showMaxFactor(num)

报错

try:
    int("asd")
except ValueError as reason:
    print("出错啦:"+ str(reason))
else:
    print("没有任何异常")

try:
    int("132")
except ValueError as reason:
    print("出错啦:"+ str(reason))
else:
    print("没有任何异常")

简洁的with语句

用with前

try:
    f = open("data.txt","w")
    for each_line in f:
        print (each_line)
except OSError as reason:
    print("出错啦：" + str(reason))
finally:
    f.close()

用with后

try:
    with open("data.txt","w") as f:
        for each_line in f:
            print (each_line)
except OSError as reason:
    print("出错啦：" + str(reason))