请写出下面各题相应的Python代码 将字符串"abcd"转换成大写 计算字符串"cd"在字符串"abcd"中出现的位置 字符串“a,b,c,d"，请用逗号分割字符串。 string ="Python is good",请将字符串里的Python替换成python,并输出替换后的结果, 有一个字符串string ="python数据类型练习.html",请从这个字符串中获得.html前面的部分, 获得字符串string ="python数据类型练习.html"的长度。 "this is a book",请将字符串里的book替换成apple "this is a book”，请用程序判断该字符串是否以this开头。 "this is a book",请用程序判断该字符串是否以apple结尾 "This IS a book",请将字符串里的大写字符转成小写字符, "This IS a book"，请将字符串里的小写字符转成大写字符！ "this is a book",字符串的末尾有一个回车符,请将其删除

1. 将字符串"abcd"转换成大写的Python代码：

string = "abcd"
string_upper = string.upper()
print(string_upper)

2. 计算字符串"cd"在字符串"abcd"中出现的位置的Python代码：

string = "abcd"
substring = "cd"
index = string.find(substring)
print(index)

3. 字符串“a,b,c,d"，用逗号分割字符串的Python代码：

string = "a,b,c,d"
string_split = string.split(",")
print(string_split)

4. 将字符串"Python is good"里的Python替换成python，并输出替换后的结果的Python代码：

string = "Python is good"
string_replace = string.replace("Python", "python")
print(string_replace)

5. 从字符串"python数据类型练习.html"中获得.html前面的部分的Python代码：

string = "python数据类型练习.html"
substring = string.split(".")[0]
print(substring)

6. 获得字符串"python数据类型练习.html"的长度的Python代码：

string = "python数据类型练习.html"
length = len(string)
print(length)

7. 将字符串"this is a book"里的book替换成apple的Python代码：

string = "this is a book"
string_replace = string.replace("book", "apple")
print(string_replace)

8. 用程序判断字符串"this is a book"是否以this开头的Python代码：

string = "this is a book"
if string.startswith("this"):
    print("Yes")
else:
    print("No")

9. 用程序判断字符串"this is a book"是否以apple结尾的Python代码：

string = "this is a book"
if string.endswith("apple"):
    print("Yes")
else:
    print("No")

10. 将字符串"This IS a book"里的大写字符转成小写字符的Python代码：

string = "This IS a book"
string_lower = string.lower()
print(string_lower)

11. 将字符串"this is a book"里的小写字符转成大写字符的Python代码：

string = "this is a book"
string_upper = string.upper()
print(string_upper)

12. 字符串"this is a book"末尾有一个回车符，请将其删除的Python代码：

string = "this is a book\n"
string_strip = string.rstrip()
print(string_strip)