python基础知识

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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

“”"
data = [1, 2, 3, 4, 5, 6, 7, 8, 9]
for i in data:
for j in data:
ji = i * j
if j > i:
break
print(i, “", j, “=”, ji, end = " “)
j += 1
print(end=”n")
i += 1
i=1
j=1
while i in data:
j = 1
while j in data:
ji = j * i
if i < j:
break
print(i, "”, j, “=”, ji, end = " “)
j += 1
print(end=”n")
i = i+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]
2. 定义一个元组: tuple_data = (1, 2, 3) => tuple_data[2] = 10
3. 定义一个字典：dict_data = {1: 2, 2: 3} => dict_data[3]

“”"
list_data = [1, 2, 3]
try:
list_data[3]
except IndexError:
print(“a”)
tuple_data = (1, 2, 3)
try:
list_data[4]=10
except IndexError:
print(“b”)
dict_data = {1: 2, 2: 3}
try:
dict_data[3]
except KeyError:
print(“c”)
“”"
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
b.读文件：
读取前三十字符所在的行
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file_obj = open(“20211028.txt”, “w”, encoding = “utf-8”)
file_obj.write(“今天是10月28号.”)
file_obj.close()
file_obj = open(“20211028.txt”, “a”, encoding = “utf-8”)
file_obj.write(“明天是10月28日.”)
file_obj.close()
file_obj = open(“20211028.txt”, encoding= “utf-8”)
data = file_obj.read(30)
file_obj.close()
print(data)
print(bytes(data, encoding= “utf-8”))

运行结果：
D:zhuomianPythonhuanjingpythonpython.exe D:/zhuomian/Python/huanjing/ysjpy/zuoye4.py
1 * 1 = 1
2 * 1 = 2 2 * 2 = 4
3 * 1 = 3 3 * 2 = 6 3 * 3 = 9
4 * 1 = 4 4 * 2 = 8 4 * 3 = 12 4 * 4 = 16
5 * 1 = 5 5 * 2 = 10 5 * 3 = 15 5 * 4 = 20 5 * 5 = 25
6 * 1 = 6 6 * 2 = 12 6 * 3 = 18 6 * 4 = 24 6 * 5 = 30 6 * 6 = 36
7 * 1 = 7 7 * 2 = 14 7 * 3 = 21 7 * 4 = 28 7 * 5 = 35 7 * 6 = 42 7 * 7 = 49
8 * 1 = 8 8 * 2 = 16 8 * 3 = 24 8 * 4 = 32 8 * 5 = 40 8 * 6 = 48 8 * 7 = 56 8 * 8 = 64
9 * 1 = 9 9 * 2 = 18 9 * 3 = 27 9 * 4 = 36 9 * 5 = 45 9 * 6 = 54 9 * 7 = 63 9 * 8 = 72 9 * 9 = 81
1 * 1 = 1
2 * 1 = 2 2 * 2 = 4
3 * 1 = 3 3 * 2 = 6 3 * 3 = 9
4 * 1 = 4 4 * 2 = 8 4 * 3 = 12 4 * 4 = 16
5 * 1 = 5 5 * 2 = 10 5 * 3 = 15 5 * 4 = 20 5 * 5 = 25
6 * 1 = 6 6 * 2 = 12 6 * 3 = 18 6 * 4 = 24 6 * 5 = 30 6 * 6 = 36
7 * 1 = 7 7 * 2 = 14 7 * 3 = 21 7 * 4 = 28 7 * 5 = 35 7 * 6 = 42 7 * 7 = 49
8 * 1 = 8 8 * 2 = 16 8 * 3 = 24 8 * 4 = 32 8 * 5 = 40 8 * 6 = 48 8 * 7 = 56 8 * 8 = 64
9 * 1 = 9 9 * 2 = 18 9 * 3 = 27 9 * 4 = 36 9 * 5 = 45 9 * 6 = 54 9 * 7 = 63 9 * 8 = 72 9 * 9 = 81
a
b
c
今天是10月28号.明天是10月28日.
b’xe4xbbx8axe5xa4xa9xe6x98xaf10xe6x9cx8828xe5x8fxb7.xe6x98x8exe5xa4xa9xe6x98xaf10xe6x9cx8828xe6x97xa5.’

Process finished with exit code 0