今日作业：
1.打印 9 * 9乘法表：
格式：
1 * 1 = 1
2 * 1 = 2 2 * 2 = 4
3 * 1 = 3 3 * 2 = 6 3 * 3 = 9
…
9 * 1 = 9 9 * 2 = 18 … 9 * 9 = 81
for i in range(1, 10):
for j in range(1, i + 1):
print(i, “*”, j, “=”, i * j, end=’ ')
print()
i = 1
while i <= 9:
j = 1
while j <= i:
print(i, “*”, j, i * j, end=" ")
j += 1
i += 1
print()
i = 1
while i <= 9:
if j <= i:
print(i, “*”, j, i * j, end=" ")
j += 1
else:
print()
i += 1
j = 1
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2.异常处理的使用：
#1) 列表超出索引: list_data = [1, 2, 3] => list_data[3]
try:
list_data = [1, 2, 3]
print(list_data[3])
except:
print(“IndexError”)
#2) 定义一个元组: tuple_data = (1, 2, 3) => tuple_data[2] = 10
try:
tuple_data = (1, 2, 3)
data = tuple_data[2] = 10
print(data)
except:
print(“TypeError”)
#3) 定义一个字典：dict_data = {1: 2, 2: 3} => dict_data[3]
try:
dict_data = {1: 2, 2: 3}
print(dict_data[3])
except:
print(“KeyError”)
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3.文件操作：
#a.写文本文件：
#一次写入多行内容
#关闭文件
#重新打开，往文件追加新的一行内容
file_obj = open(“file.txt”, “w”, encoding=“UTF-8”)
file_obj.writelines([“adsn”, “dasdadn”, “sdacasdn”])
file_obj.close()
file_obj = open(“file.txt”, “a”, encoding=“utf-8”)
file_obj.writelines([“dadsn”, “dadasdn”])
file_obj.close()
#b.读文件：
#读取前三十字符所在的行
file_obj = open(“file.txt”, “r”, encoding=“utf-8”)
data = file_obj.readlines(30)
print(data)
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运行结果：
在这里插入图片描述
在这里插入图片描述
